Cytotoxic benzodiazepine derivatives

ABSTRACT

The invention relates to novel benzodiazepine derivatives with antiproliferative activity and more specifically to novel benzodiazepine compounds of formula (I)-(VI). The invention also provides conjugates of the benzodiazepine compounds linked to a cell-binding agent. The invention further provides compositions and methods useful for inhibiting abnormal cell growth or treating a proliferative disorder in a mammal using the compounds or conjugates of the invention.

REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 14/843,520, filed Sep. 2, 2015, which claims the benefit of thefiling date under 35 U.S.C. §119(e), of U.S. Provisional Application No.62/045,248, filed on Sep. 3, 2014, U.S. Provisional Application No.62/087,040, filed on Dec. 3, 2014, U.S. Provisional Application No.62/149,370, filed on Apr. 17, 2015, and U.S. Provisional Application No.62/164,305, filed on May 20, 2015, the entire contents of each of which,including all drawings, formulae, specifications, and claims, areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to novel cytotoxic compounds, andcytotoxic conjugates comprising these cytotoxic compounds andcell-binding agents. More specifically, this invention relates to novelbenzodiazepine compounds, derivatives thereof, intermediates thereof,conjugates thereof, and pharmaceutically acceptable salts thereof, whichare useful as medicaments, in particular as anti-proliferative agents.

BACKGROUND OF THE INVENTION

Benzodiazepine derivatives are useful compounds for treating variousdisorders, and include medicaments such as, antiepileptics(imidazo[2,1-b][1,3,5]benzothiadiazepines, U.S. Pat. No. 4,444,688; U.S.Pat. No. 4,062,852), antibacterials(pyrimido[1,2-c][1,3,5]benzothiadiazepines, GB 1476684), diuretics andhypotensives (pyrrolo(1,2-b)[1,2,5]benzothiadiazepine 5,5 dioxide, U.S.Pat. No. 3,506,646), hypolipidemics (WO 03091232), anti-depressants(U.S. Pat. No. 3,453,266); osteoporosis (JP 2138272).

It has been shown in animal tumor models that benzodiazepinederivatives, such as pyrrolobenzodiazepines (PBDs), act as anti-tumoragents (N-2-imidazolyl alkyl substituted1,2,5-benzothiadiazepine-1,1-dioxide, U.S. Pat. No. 6,156,746),benzo-pyrido or dipyrido thiadiazepine (WO 2004/069843),pyrrolo[1,2-b][1,2,5]benzothiadiazepines andpyrrolo[1,2-b][1,2,5]benzodiazepine derivatives (WO2007/015280),tomaymycin derivatives (e.g., pyrrolo[1,4]benzodiazepines), such asthose described in WO 00/12508, WO2005/085260, WO2007/085930, and EP2019104. Benzodiazepines are also known to affect cell growth anddifferentiation (Kamal A., et al., Bioorg Med Chem. 2008 Aug. 15;16(16):7804-10 (and references cited therein); Kumar R, Mini Rev MedChem. 2003 June; 3(4):323-39 (and references cited therein); Bednarski JJ, et al., 2004; Sutter A. P, et al., 2002; Blatt N B, et al., 2002),Kamal A. et al., Current Med. Chem., 2002; 2; 215-254, Wang J-J., J.Med. Chem., 2206; 49:1442-1449, Alley M. C. et al., Cancer Res. 2004;64:6700-6706, Pepper C. J., Cancer Res 2004; 74:6750-6755, Thurston D.E. and Bose D. S., Chem Rev 1994; 94:433-465; and Tozuka, Z., et al.,Journal of Antibiotics, (1983) 36; 1699-1708. General structure of PBDsis described in US Publication Number 20070072846. The PBDs differ inthe number, type and position of substituents, in both their aromatic Arings and pyrrolo C rings, and in the degree of saturation of the Cring. Their ability to form an adduct in the minor groove and crosslinkDNA enables them to interfere with DNA processing, hence their potentialfor use as antiproliferative agents.

The first pyrrolobenzodiazepine to enter the clinic, SJG-136 (NSC694501) is a potent cytotoxic agent that causes DNA inter-strandcrosslinks (S. G Gregson et al., 2001, J. Med. Chem., 44: 737-748; M. C.Alley et al., 2004, Cancer Res., 64: 6700-6706; J. A. Hartley et al.,2004, Cancer Res., 64: 6693-6699; C. Martin et al., 2005, Biochemistry.,44: 4135-4147; S. Arnould et al., 2006, Mol. Cancer Ther., 5:1602-1509). Results from a Phase I clinical evaluation of SJG-136revealed that this drug was toxic at extremely low doses (maximumtolerated dose of 45 μg/m², and several adverse effects were noted,including vascular leak syndrome, peripheral edema, liver toxicity andfatigue. DNA damage was noted at all doses in circulating lymphocytes(D. Hochhauser et al., 2009, Clin. Cancer Res., 15: 2140-2147). Thus,there exists a need for improved benzodiazepine derivatives that areless toxic and still therapeutically active for treating a variety ofproliferative disease states, such as cancer.

SUMMARY OF THE INVENTION

The novel benzodiazepine compounds described herein and the conjugatesthereof have surprisingly high potency againt various tumor cells.

One object of the invention is to provide a cytotoxic compoundrepresented by any one of the following formulas:

or a pharmaceutically acceptable salt thereof, wherein:

-   -   one of L′, L″, and L′″ is represented by the following formula:

—Z₁—P—Z₂—R_(x)-J  (A)

-   -    and the other two are the same or different, and are        independently selected from —H, an optionally substituted        linear, branched or cyclic alkyl, alkenyl or alkynyl having from        1 to 10 carbon atoms, a polyethylene glycol unit        —(CH₂CH₂O)_(n)—R^(c), halogen, guanidinium [—NH(C═NH)NH₂], —OR,        —NR′R″, —NO₂, —NR′COR″, —SR, —SOR′, —SO₂R′, —SO₃H, —OSO₃H,        —SO₂NR′R″, cyano, an azido, —COR′, —OCOR′, and —OCONR′R″;    -   one of the Z₁ and Z₂ is —C(═O)—, and the other is —NR₅—;    -   P is an amino acid residue or a peptide containing between 2 to        20 amino acid residues;    -   R_(x) is an optionally substituted linear, branched or cyclic        alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms;    -   J is a moiety comprising a reactive group that is capable of        covalently linking the cytotoxic compound to a cell-binding        agent;    -   the double line        between N and C represents a single bond or a double bond,        provided that when it is a double bond X is absent and Y is —H,        or a linear or branched alkyl having 1 to 4 carbon atoms, and        when it is a single bond, X is —H or an amine protecting moiety;    -   Y is a leaving group selected from —OR, —OCOR′, —OCOOR′,        —OCONR′R″, —NR′R″, —NR′COR″, —NR′NR′R″, an optionally        substituted 5- or 6-membered nitrogen-containing heterocycle        (e.g., piperidine, tetrahydropyrrole, pyrazole, morpholine, etc.        attached through the nitrogen atom), a guanidinum represented by        —NR′(C═NH)NR′R″, an amino acid residue, or a peptide represented        by —NRCOP′, —SR, —SOR′, halogen, cyano, azido, —OSO₃H, sulfite        (—SO₃H or —SO₂H), metabisulfite (H₂S₂O₅), mono-, di-, tri-, and        tetra-thiophosphate (PO₃SH₃, PO₂S₂H₂, POS₃H₂, PS₄H₂), thio        phosphate ester (R^(i)O)₂PS(OR^(i)), R^(i)S—, R^(i)SO, R^(i)SO₂,        R^(i)SO₃, thiosulfate (HS₂O₃), dithionite (HS₂O₄),        phosphorodithioate (P(═S)(OR^(k′))(S)(OH)), hydroxamic acid        (R^(k′)C(═O)NOH), and formaldehyde sulfoxylate (HOCH₂SO₂ ⁻) or a        mixture thereof, wherein R^(i) is a linear or branched alkyl        having 1 to 10 carbon atoms and is substituted with at least one        substituent selected from —N(R^(j))₂, —CO₂H, —SO₃H, and —PO₃H;        R^(i) can be further optionally substituted with a substituent        for an alkyl described herein; R^(j) is a linear or branched        alkyl having 1 to 6 carbon atoms; R^(k′) is a linear, branched        or cyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms,        aryl, heterocyclyl or heteroaryl;    -   P′ is an amino acid residue or a polypeptide containing between        2 to 20 amino acid residues,    -   R, for each occurrence, is independently selected from the group        consisting of —H, an optionally substituted linear, branched or        cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon        atoms, a polyethylene glycol unit —(CH₂CH₂O)_(n)—R^(c), an        optionally substituted aryl having 6 to 18 carbon atoms, an        optionally substituted 5- to 18-membered heteroaryl ring        containing one or more heteroatoms independently selected from        nitrogen, oxygen, and sulfur, or an optionally substituted 3- to        18-membered heterocyclic ring containing 1 to 6 heteroatoms        independently selected from O, S, N and P;    -   R′ and R″ are each independently selected from —H, —OH, —OR,        —NHR, —NR₂, —COR, an optionally substituted linear, branched or        cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon        atoms, a polyethylene glycol unit —(CH₂CH₂O)_(n)—R^(c), and an        optionally substituted 3- to 18-membered heterocyclic ring        having 1 to 6 heteroatoms independently selected from O, S, N        and P;    -   R^(c) is —H or an optionally substituted linear or branched        alkyl having 1 to 4 carbon atoms;    -   n is an integer from 1 to 24;    -   X′ is selected from —H, an amine-protecting group, an optionally        substituted linear, branched or cyclic alkyl, alkenyl or alkynyl        having from 1 to 10 carbon atoms, a polyethylene glycol unit        —(CH₂CH₂O)_(n)—R^(c), an optionally substituted aryl having 6 to        18 carbon atoms, an optionally substituted 5- to 18-membered        heteroaryl ring containing one or more heteroatoms independently        selected from nitrogen, oxygen, and sulfur, and an optionally        substituted 3- to 18-membered heterocyclic ring containing 1 to        6 heteroatoms independently selected from O, S, N and P;    -   Y′ is selected from —H, an oxo group, an optionally substituted        linear, branched or cyclic alkyl, alkenyl or alkynyl having from        1 to 10 carbon atoms, an optionally substituted 6- to        18-membered aryl, an optionally substituted 5- to 18-membered        heteroaryl ring containing one or more heteroatoms independently        selected from nitrogen, oxygen, and sulfur, an optionally        substituted 3- to 18-membered heterocyclic ring having 1 to 6        heteroatoms;    -   R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ are each independently        selected from the group consisting of —H, an optionally        substituted linear, branched or cyclic alkyl, alkenyl or alkynyl        having from 1 to 10 carbon atoms, a polyethylene glycol unit        —(CH₂CH₂O)_(n)—R^(c), halogen, guanidinium [—NH(C═NH)NH₂], —OR,        —NR′R″, —NO₂, —NCO, —NR′COR″, —SR, —SOR′, —SO₂R′, —SO₃—H,        —OSO₃H, —SO₂NR′R″, cyano, an azido, —COR′, —OCOR′, and        —OCONR′R″;    -   R₆ is —H, —R, —OR, —SR, —NR′R″, —NO₂, or halogen;    -   G is —CH— or —N—;    -   A and A′ are the same or different, and are independently        selected from —O—, oxo (—C(═O)—), —CRR′O—, —CRR′—, —S—, —CRR′S—,        —NR₅ and —CRR′N(R₅)—; and    -   R₅ for each occurrence is independently —H or an optionally        substituted linear or branched alkyl having 1 to 10 carbon        atoms.

In one embodiment, for compounds of structural formulas (I)-(VI), G is—CH—.

A second object of the invention is to provide conjugates of cellbinding agents with the novel benzodiazepine compounds or derivativesthereof of the present invention. These conjugates are useful astherapeutic agents, which are delivered specifically to target cells andare cytotoxic.

Specifically, a conjugate of the invention may comprise: a cytotoxiccompound and a cell-binding agent (CBA), wherein the cytotoxic compoundis covalently linked to the CBA, and wherein said cytotoxic compound isrepresented by any one of the following formulas:

or a pharmaceutically acceptable salt thereof, wherein:

-   -   one of L′, L″, and L′″ is represented by the following formula:

—Z₁—P—Z₂—R_(x)-J′  (A′)

optionally substituted linear, branched or cyclic alkyl, alkenyl oralkynyl having from 1 to 10 carbon atoms, a polyethylene glycol unit—(CH₂CH₂O)_(n)—R^(c), halogen, guanidinium [—NH(C═NH)NH₂], —OR, —NR′R″,—NO₂, —NR′COR″, —SR, a sulfoxide represented by —SOR′, a sulfonerepresented by —SO₂R′, a sulfonate —SO₃M, a sulfate —OSO₃M, asulfonamide represented by —SO₂NR′R″, cyano, an azido, —COR′, —OCOR′,and —OCONR′R″;

-   -   J′ is a moiety comprising a linking group that is covalently        linked to the cell-binding agent; and    -   the remaining of the variables are as described above for        formulas (I)-(VI).

In one embodiment, for conjugates of structural formulas (I′)-(VI′), Gis —CH—.

In another embodiment, for conjugates of structural formulas (I′)-(VI′),the cell-binding agent is an anti-folate receptor antibody or anantibody fragment thereof. More specifically, the anti-folate receptorantibody is huMOV19 antibody.

In yet another embodiment, for conjugates of structural formulas(I′)-(VI′), the cell-binding agent is an anti-EGFR antibody or anantibody fragment thereof. In one embodiment, the anti-EGFR antibody isa non-antagonist antibody, including, for example, the antibodiesdescribed in WO2012058592, herein incorporated by reference. In anotherembodiment, the anti-EGFR antibody is a non-functional antibody, forexample, humanized ML66. More specifically, the anti-EGFR antibody ishuML66.

The present invention also includes a composition (e.g., apharmaceutical composition) comprising novel benzodiazepine compounds,derivatives thereof, or conjugates thereof, (and/or solvates, hydratesand/or salts thereof) and a carrier (a pharmaceutically acceptablecarrier). The present invention additionally includes a composition(e.g., a pharmaceutical composition) comprising novel benzodiazepinecompounds, derivatives thereof, or conjugates thereof (and/or solvates,hydrates and/or salts thereof), and a carrier (a pharmaceuticallyacceptable carrier), further comprising a second therapeutic agent. Thepresent compositions are useful for inhibiting abnormal cell growth ortreating a proliferative disorder in a mammal (e.g., human). The presentcompositions are useful for treating conditions such as cancer,rheumatoid arthritis, multiple sclerosis, graft versus host disease(GVHD), transplant rejection, lupus, myositis, infection, immunedeficiency such as AIDS, and inflammatory diseases in a mammal (e.g.,human).

The present invention includes a method of inhibiting abnormal cellgrowth or treating a proliferative disorder in a mammal (e.g., human)comprising administering to said mammal a therapeutically effectiveamount of novel benzodiazepine compounds, derivatives thereof, orconjugates thereof, (and/or solvates and salts thereof) or a compositionthereof, alone or in combination with a second therapeutic agent.

The present invention includes a method of synthesizing and using novelbenzodiazepine compounds, derivatives thereof, and conjugates thereoffor in vitro, in situ, and in vivo diagnosis or treatment of mammaliancells, organisms, or associated pathological conditions.

The compounds of this invention, derivatives thereof, or conjugatesthereof, and compositions comprising them, are useful for treating orlessening the severity of disorders, such as, characterized by abnormalgrowth of cells (e.g., cancer). Other applications for compounds andconjugates of this invention include, but are not limited to, treatingconditions such as cancer, rheumatoid arthritis, multiple sclerosis,graft versus host disease (GVHD), transplant rejection, lupus, myositis,infection, immune deficiency such as AIDS and inflammatory diseases in amammal (e.g., human).

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows binding affinity of huMOV19-14 conjugate as compared tounconjugated antibody huMOV19 on T47D cells.

FIG. 2 shows in vitro cytotoxicity and specificity of huMOV19-14conjugate.

FIG. 3 shows that the huMOV19-14 conjugate exhibits weak bystandercytotoxic effect on the neighboring antigen-negative cells.

FIGS. 4A, 4B and 4C show in vitro cytotoxicity of huMy9-6-14 conjugateagainst various cell lines.

FIGS. 5A and 5B show that the huMy9-6-14 conjugate exhibits bystandercytotoxic effect on the neighboring antigen-negative cells.

FIG. 6 shows in vivo efficacy of huMOV19-80 and huMOV19-90 conjugates inNCI-H2110 bearing SCID mice.

FIG. 7A-7D show mass spectrometry profiles of representative conjugatesof the present invention.

FIG. 8 shows mass spectrometry profile of huML66-90 conjugate.

FIG. 9 shows in vitro cytotoxicity and specificity of huML66-90conjugate.

FIGS. 10, 11 and 12 show in vitro cytotoxicity and specificity ofhuMOV19-90 conjugate.

FIG. 13 shows that the huMOV19-90 conjugate exhibits strong bystandercytotoxic effect on the neighboring antigen-negative cells.

FIG. 14 shows in vivo efficacy of huMOV19-90 conjugate in NCI-H2110bearing SCID mice.

FIGS. 15A and 15B shows binding affinity of huMOV19-90 conjugate ascompared to unconjugated antibody huMOV19 on T47D cells.

FIG. 16 shows mass spectrometry profiles of a representative conjugatesof the present invention.

FIG. 17 shows in vivo efficacy of huML66-90 conjugate in NCI-H1703 NSCLCbearing SCID mice.

FIG. 18 shows pharmacokinetics of huMOV19-90 in CD-1 mice.

FIGS. 19A and 19B show the structure of huMOV19-90 conjugate (FIG. 19A),and a scheme for incubation, purification, and isolation of catabolitesfrom huMOV19-90 conjugate formed in KB cervical cancer cells in vitro(FIG. 19B). The three catabolites identified by LC-MS are shown alongwith the calculated mass.

FIG. 20 shows binding affinity of huMOV19-107 conjugate as compared tounconjugated antibody huMOV19 on T47D cells.

FIGS. 21A, 21B and 21C show in vitro cytotoxicity and specificity ofhuMOV19-90 and huMOV19-107 conjugates.

FIG. 22 shows in vivo efficacy of huMOV19-90 conjugate in bearing SCIDmice bearing NCI-H2110 NSCLC xenografts.

FIG. 23 shows in vivo efficacy of huMOV19-90 conjugate in SCID micebearing Hec-1b endometrial xenografts.

FIG. 24 shows in vivo efficacy of huMOV19-90 conjugate in SCID micebearing Ishikawa endometrial xenografts.

FIG. 25 shows in vivo efficacy of huMOV19-107 conjugate in bearing SCIDmice bearing NCI-H2110 NSCLC xenografts.

FIG. 26 shows binding affinity of huCD123-6Gv4.7S3-90 conjugate ascompared to the unconjugated antibody on HNT-34 cells.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to certain embodiments of theinvention, examples of which are illustrated in the accompanyingstructures and formulas. While the invention will be described inconjunction with the enumerated embodiments, it will be understood thatthey are not intended to limit the invention to those embodiments. Onthe contrary, the invention is intended to cover all alternatives,modifications, and equivalents which may be included within the scope ofthe present invention as defined by the claims. One skilled in the artwill recognize many methods and materials similar or equivalent to thosedescribed herein, which could be used in the practice of the presentinvention.

It should be understood that any of the embodiments described herein,including those described under different aspects of the invention(e.g., compounds, compound-linker molecules, conjugates, compositions,methods of making and using) and different parts of the specification(including embodiments described only in the Examples) can be combinedwith one or more other embodiments of the invention, unless explicitlydisclaimed or improper. Combination of embodiments are not limited tothose specific combinations claimed via the multiple dependent claims.

Definitions

As used herein, the term “cell-binding agent” or “CBA” refers to acompound that can bind a cell (e.g., on a cell-surface ligand) or bind aligand associated with or proximate to the cell, preferably in aspecific manner. In certain embodiments, binding to the cell or a ligandon or near the cell is specific. The CBA may include peptides andnon-peptides.

“Linear or branched alkyl” as used herein refers to a saturated linearor branched-chain monovalent hydrocarbon radical of one to twenty carbonatoms. Examples of alkyl include, but are not limited to, methyl, ethyl,1-propyl, 2-propyl, 1-butyl, 2-methyl-1-propyl, —CH₂CH(CH₃)₂), 2-butyl,2-methyl-2-propyl, 1-pentyl, 2-pentyl 3-pentyl, 2-methyl-2-butyl,3-methyl-2-butyl, 3-methyl-1-butyl, 2-methyl-1-butyl, 1-hexyl), 2-hexyl,3-hexyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl,3-methyl-3-pentyl, 2-methyl-3-pentyl, 2,3-dimethyl-2-butyl,3,3-dimethyl-2-butyl, 1-heptyl, 1-octyl, and the like. Preferably, thealkyl has one to ten carbon atoms. More preferably, the alkyl has one tofour carbon atoms.

“Linear or branched alkenyl” refers to linear or branched-chainmonovalent hydrocarbon radical of two to twenty carbon atoms with atleast one site of unsaturation, i.e., a carbon-carbon, double bond,wherein the alkenyl radical includes radicals having “cis” and “trans”orientations, or alternatively, “E” and “Z” orientations. Examplesinclude, but are not limited to, ethylenyl or vinyl (—CH═CH₂), allyl(—CH₂CH═CH₂), and the like. Preferably, the alkenyl has two to tencarbon atoms. More preferably, the alkyl has two to four carbon atoms.

“Linear or branched alkynyl” refers to a linear or branched monovalenthydrocarbon radical of two to twenty carbon atoms with at least one siteof unsaturation, i.e., a carbon-carbon, triple bond. Examples include,but are not limited to, ethynyl, propynyl, 1-butynyl, 2-butynyl,1-pentynyl, 2-pentynyl, 3-pentynyl, hexynyl, and the like. Preferably,the alkynyl has two to ten carbon atoms. More preferably, the alkynylhas two to four carbon atoms.

The term “carbocycle,” “carbocyclyl” and “carbocyclic ring” refer to amonovalent non-aromatic, saturated or partially unsaturated ring having3 to 12 carbon atoms as a monocyclic ring or 7 to 12 carbon atoms as abicyclic ring. Bicyclic carbocycles having 7 to 12 atoms can bearranged, for example, as a bicyclo [4,5], [5,5], [5,6], or [6,6]system, and bicyclic carbocycles having 9 or 10 ring atoms can bearranged as a bicyclo [5,6] or [6,6] system, or as bridged systems suchas bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane. Examples of monocyclic carbocycles include, but are notlimited to, cyclopropyl, cyclobutyl, cyclopentyl, 1-cyclopent-1-enyl,1-cyclopent-2-enyl, 1-cyclopent-3-enyl, cyclohexyl, 1-cyclohex-1-enyl,1-cyclohex-2-enyl, 1-cyclohex-3-enyl, cyclohexadienyl, cycloheptyl,cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl, and thelike.

The terms “cyclic alkyl” and “cycloalkyl” can be used interchangeably.They refer to a monovalent saturated carbocyclic ring radical.Preferably, the cyclic alkyl is 3 to 7 membered monocyclic ring radical.More preferably, the cyclic alkyl is cyclohexyl.

The term “cyclic alkenyl” refers to a carbocyclic ring radical having atleast one double bond in the ring structure.

The term “cyclic alkynyl” refers to a carbocyclic ring radical having atleast one triple bond in the ring structure.

“Aryl” means a monovalent aromatic hydrocarbon radical of 6-18 carbonatoms derived by the removal of one hydrogen atom from a single carbonatom of a parent aromatic ring system. Some aryl groups are representedin the exemplary structures as “Ar.” Aryl includes bicyclic radicalscomprising an aromatic ring fused to a saturated, partially unsaturatedring, or aromatic carbocyclic or heterocyclic ring. Typical aryl groupsinclude, but are not limited to, radicals derived from benzene (phenyl),substituted benzenes, naphthalene, anthracene, indenyl, indanyl,1,2-dihydronapthalene, 1,2,3,4-tetrahydronapthyl, and the like.Preferably, aryl is phenyl group.

The terms “heterocycle,” “heterocyclyl,” and “heterocyclic ring” areused interchangeably herein and refer to a saturated or a partiallyunsaturated (i.e., having one or more double and/or triple bonds withinthe ring) carbocyclic radical of 3 to 18 ring atoms in which at leastone ring atom is a heteroatom selected from nitrogen, oxygen,phosphorus, and sulfur, the remaining ring atoms being C, where one ormore ring atoms is optionally substituted independently with one or moresubstituents described below. A heterocycle may be a monocycle having 3to 7 ring members (2 to 6 carbon atoms and 1 to 4 heteroatoms selectedfrom N, O, P, and S) or a bicycle having 7 to 10 ring members (4 to 9carbon atoms and 1 to 6 heteroatoms selected from N, O, P, and S), forexample: a bicyclo [4,5], [5,5], [5,6], or [6,6] system. Heterocyclesare described in Paquette, Leo A.; “Principles of Modern HeterocyclicChemistry” (W. A. Benjamin, New York, 1968), particularly Chapters 1, 3,4, 6, 7, and 9; “The Chemistry of Heterocyclic Compounds, A series ofMonographs” (John Wiley & Sons, New York, 1950 to present), inparticular Volumes 13, 14, 16, 19, and 28; and J. Am. Chem. Soc. (1960)82:5566. “Heterocyclyl” also includes radicals where heterocycleradicals are fused with a saturated, partially unsaturated ring, oraromatic carbocyclic or heterocyclic ring. Examples of heterocyclicrings include, but are not limited to, pyrrolidinyl, tetrahydrofuranyl,dihydrofuranyl, tetrahydrothienyl, tetrahydropyranyl, dihydropyranyl,tetrahydrothiopyranyl, piperidino, morpholino, thiomorpholino,thioxanyl, piperazinyl, homopiperazinyl, azetidinyl, oxetanyl,thietanyl, homopiperidinyl, oxepanyl, thiepanyl, oxazepinyl, diazepinyl,thiazepinyl, 2-pyrrolinyl, 3-pyrrolinyl, indolinyl, 2H-pyranyl,4H-pyranyl, dioxanyl, 1,3-dioxolanyl, pyrazolinyl, dithianyl,dithiolanyl, dihydropyranyl, dihydrothienyl, dihydrofuranyl,pyrazolidinylimidazolinyl, imidazolidinyl, 3-azabicyco[3.1.0]hexanyl,3-azabicyclo[4.1.0]heptanyl, and azabicyclo[2.2.2]hexanyl. Spiromoieties are also included within the scope of this definition. Examplesof a heterocyclic group wherein ring atoms are substituted with oxo (═O)moieties are pyrimidinonyl and 1,1-dioxo-thiomorpholinyl.

The term “heteroaryl” refers to a monovalent aromatic radical of 5- or6-membered rings, and includes fused ring systems (at least one of whichis aromatic) of 5-18 atoms, containing one or more heteroatomsindependently selected from nitrogen, oxygen, and sulfur. Examples ofheteroaryl groups are pyridinyl (including, for example,2-hydroxypyridinyl), imidazolyl, imidazopyridinyl, pyrimidinyl(including, for example, 4-hydroxypyrimidinyl), pyrazolyl, triazolyl,pyrazinyl, tetrazolyl, furyl, thienyl, isoxazolyl, thiazolyl, oxazolyl,isothiazolyl, pyrrolyl, quinolinyl, isoquinolinyl, indolyl,benzimidazolyl, benzofuranyl, cinnolinyl, indazolyl, indolizinyl,phthalazinyl, pyridazinyl, triazinyl, isoindolyl, pteridinyl, purinyl,oxadiazolyl, triazolyl, thiadiazolyl, furazanyl, benzofurazanyl,benzothiophenyl, benzothiazolyl, benzoxazolyl, quinazolinyl,quinoxalinyl, naphthyridinyl, and furopyridinyl.

The heterocycle or heteroaryl groups may be carbon (carbon-linked) ornitrogen (nitrogen-linked) attached where such is possible. By way ofexample and not limitation, carbon bonded heterocycles or heteroarylsare bonded at position 2, 3, 4, 5, or 6 of a pyridine, position 3, 4, 5,or 6 of a pyridazine, position 2, 4, 5, or 6 of a pyrimidine, position2, 3, 5, or 6 of a pyrazine, position 2, 3, 4, or 5 of a furan,tetrahydrofuran, thiofuran, thiophene, pyrrole or tetrahydropyrrole,position 2, 4, or 5 of an oxazole, imidazole or thiazole, position 3, 4,or 5 of an isoxazole, pyrazole, or isothiazole, position 2 or 3 of anaziridine, position 2, 3, or 4 of an azetidine, position 2, 3, 4, 5, 6,7, or 8 of a quinoline or position 1, 3, 4, 5, 6, 7, or 8 of anisoquinoline.

By way of example and not limitation, nitrogen bonded heterocycles orheteroaryls are bonded at position 1 of an aziridine, azetidine,pyrrole, pyrrolidine, 2-pyrroline, 3-pyrroline, imidazole,imidazolidine, 2-imidazoline, 3-imidazoline, pyrazole, pyrazoline,2-pyrazoline, 3-pyrazoline, piperidine, piperazine, indole, indoline,1H-indazole, position 2 of a isoindole, or isoindoline, position 4 of amorpholine, and position 9 of a carbazole, or O-carboline.

The heteroatoms present in heteroaryl or heterocyclcyl include theoxidized forms such as NO, SO, and SO₂.

The term “halo” or “halogen” refers to F, Cl, Br or I.

The alkyl, alkenyl, alkynyl, cyclic alkyl, cyclic alkenyl, cyclicalkynyl, carbocyclyl, aryl, heterocyclyl and heteroaryl described abovecan be optionally substituted with one more (e.g., 2, 3, 4, 5, 6 ormore) substituents.

If a substituent is described as being “substituted,” a non-hydrogensubstituent is in the place of a hydrogen substituent on a carbon,oxygen, sulfur or nitrogen of the substituent. Thus, for example, asubstituted alkyl substituent is an alkyl substituent wherein at leastone non-hydrogen substituent is in the place of a hydrogen substituenton the alkyl substituent. To illustrate, monofluoroalkyl is alkylsubstituted with a fluoro substituent, and difluoroalkyl is alkylsubstituted with two fluoro substituents. It should be recognized thatif there is more than one substitution on a substituent, eachnon-hydrogen substituent may be identical or different (unless otherwisestated).

If a substituent is described as being “optionally substituted,” thesubstituent may be either (1) not substituted, or (2) substituted. If acarbon of a substituent is described as being optionally substitutedwith one or more of a list of substituents, one or more of the hydrogenson the carbon (to the extent there are any) may separately and/ortogether be replaced with an independently selected optionalsubstituent. If a nitrogen of a substituent is described as beingoptionally substituted with one or more of a list of substituents, oneor more of the hydrogens on the nitrogen (to the extent there are any)may each be replaced with an independently selected optionalsubstituent. One exemplary substituent may be depicted as —NR′ R″,wherein R′ and R″ together with the nitrogen atom to which they areattached, may form a heterocyclic ring. The heterocyclic ring formedfrom R′ and R″ together with the nitrogen atom to which they areattached may be partially or fully saturated. In one embodiment, theheterocyclic ring consists of 3 to 7 atoms. In another embodiment, theheterocyclic ring is selected from the group consisting of pyrrolyl,imidazolyl, pyrazolyl, triazolyl, tetrazolyl, isoxazolyl, pyridyl andthiazolyl.

This specification uses the terms “substituent,” “radical,” and “group”interchangeably.

If a group of substituents are collectively described as beingoptionally substituted by one or more of a list of substituents, thegroup may include: (1) unsubstitutable substituents, (2) substitutablesubstituents that are not substituted by the optional substituents,and/or (3) substitutable substituents that are substituted by one ormore of the optional substituents.

If a substituent is described as being optionally substituted with up toa particular number of non-hydrogen substituents, that substituent maybe either (1) not substituted; or (2) substituted by up to thatparticular number of non-hydrogen substituents or by up to the maximumnumber of substitutable positions on the substituent, whichever is less.Thus, for example, if a substituent is described as a heteroaryloptionally substituted with up to 3 non-hydrogen substituents, then anyheteroaryl with less than 3 substitutable positions would be optionallysubstituted by up to only as many non-hydrogen substituents as theheteroaryl has substitutable positions. Such substituents, innon-limiting examples, can be selected from a linear, branched or cyclicalkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, aryl,heteroaryl, heterocyclyl, halogen, guanidinium [—NH(C═NH)NH₂], —OR¹⁰⁰,NR¹⁰¹R¹⁰², —NO₂, —NR¹⁰¹COR¹⁰², —SR¹⁰⁰, a sulfoxide represented by—SOR¹⁰¹, a sulfone represented by —SO₂R¹⁰¹, a sulfonate —SO₃M, a sulfate—OSO₃M, a sulfonamide represented by —SO₂NR¹⁰¹R¹⁰², cyano, an azido,—COR¹⁰¹, —OCOR¹⁰¹, —OCONR¹⁰¹R¹⁰² and a polyethylene glycol unit(—CH₂CH₂O)_(n)R¹⁰¹ wherein M is H or a cation (such as Na⁺ or K⁺); R¹⁰¹,R¹⁰² and R¹⁰³ are each independently selected from H, linear, branchedor cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, apolyethylene glycol unit (—CH₂CH₂O)_(n)—R¹⁰⁴, wherein n is an integerfrom 1 to 24, an aryl having from 6 to 10 carbon atoms, a heterocyclicring having from 3 to 10 carbon atoms and a heteroaryl having 5 to 10carbon atoms; and R¹⁰⁴ is H or a linear or branched alkyl having 1 to 4carbon atoms, wherein the alkyl, alkenyl, alkynyl, aryl, heteroaryl andheterocyclyl in the groups represented by R¹⁰⁰, R¹⁰¹, R¹⁰², R¹⁰³ andR¹⁰⁴ are optionally substituted with one or more (e.g., 2, 3, 4, 5, 6 ormore) substituents independently selected from halogen, —OH, —CN, —NO₂and unsubstituted linear or branched alkyl having 1 to 4 carbon atoms.Preferably, the substituents for the optionally substituted alkyl,alkenyl, alkynyl, cyclic alkyl, cyclic alkenyl, cyclic alkynyl,carbocyclyl, aryl, heterocyclyl and heteroaryl described above includehalogen, —CN, —NR¹⁰²R¹⁰³, —CF₃, —OR¹⁰¹, aryl, heteroaryl, heterocyclyl,—SR¹⁰¹, —SOR¹⁰¹, —SO₂R¹⁰¹ and —SO₃M.

The term “compound” or “cytotoxic compound,” “cytotoxic dimer” and“cytotoxic dimer compound” are used interchangeably. They are intendedto include compounds for which a structure or formula or any derivativethereof has been disclosed in the present invention or a structure orformula or any derivative thereof that has been incorporated byreference. The term also includes, stereoisomers, geometric isomers,tautomers, solvates, metabolites, salts (e.g., pharmaceuticallyacceptable salts) and prodrugs, and prodrug salts of a compound of allthe formulae disclosed in the present invention. The term also includesany solvates, hydrates, and polymorphs of any of the foregoing. Thespecific recitation of “stereoisomers,” “geometric isomers,”“tautomers,” “solvates,” “metabolites,” “salt” “prodrug,” “prodrugsalt,” “conjugates,” “conjugates salt,” “solvate,” “hydrate,” or“polymorph” in certain aspects of the invention described in thisapplication shall not be interpreted as an intended omission of theseforms in other aspects of the invention where the term “compound” isused without recitation of these other forms.

The term “conjugate” as used herein refers to a compound describedherein or a derivative thereof that is linked to a cell binding agent.

The term “linkable to a cell binding agent” as used herein refers to thecompounds described herein or derivates thereof comprising at least onelinking group or a precursor thereof suitable to bond these compounds orderivatives thereof to a cell binding agent.

The term “precursor” of a given group refers to any group which may leadto that group by any deprotection, a chemical modification, or acoupling reaction.

The term “linked to a cell binding agent” refers to a conjugate moleculecomprising at least one of the compounds described herein (e.g.,compounds of formula (I)-(IV) and (VIII)-(XI) and drug-linker compoundsdescribe herein), or derivative thereof bound to a cell binding agentvia a suitable linking group or a precursor thereof.

The term “chiral” refers to molecules which have the property ofnon-superimposability of the mirror image partner, while the term“achiral” refers to molecules which are superimposable on their mirrorimage partner.

The term “stereoisomer” refers to compounds which have identicalchemical constitution and connectivity, but different orientations oftheir atoms in space that cannot be interconverted by rotation aboutsingle bonds.

“Diastereomer” refers to a stereoisomer with two or more centers ofchirality and whose molecules are not mirror images of one another.Diastereomers have different physical properties, e.g. melting points,boiling points, spectral properties, and reactivities. Mixtures ofdiastereomers may separate under high resolution analytical proceduressuch as crystallization, electrophoresis and chromatography.

“Enantiomers” refer to two stereoisomers of a compound which arenon-superimposable mirror images of one another.

Stereochemical definitions and conventions used herein generally followS. P. Parker, Ed., McGraw-Hill Dictionary of Chemical Terms (1984)McGraw-Hill Book Company, New York; and Eliel, E. and Wilen, S.,“Stereochemistry of Organic Compounds,” John Wiley & Sons, Inc., NewYork, 1994. The compounds of the invention may contain asymmetric orchiral centers, and therefore exist in different stereoisomeric forms.It is intended that all stereoisomeric forms of the compounds of theinvention, including but not limited to, diastereomers, enantiomers andatropisomers, as well as mixtures thereof such as racemic mixtures, formpart of the present invention. Many organic compounds exist in opticallyactive forms, i.e., they have the ability to rotate the plane ofplane-polarized light. In describing an optically active compound, theprefixes D and L, or R and S, are used to denote the absoluteconfiguration of the molecule about its chiral center(s). The prefixes dand l or (+) and (−) are employed to designate the sign of rotation ofplane-polarized light by the compound, with (−) or l meaning that thecompound is levorotatory. A compound prefixed with (+) or d isdextrorotatory. For a given chemical structure, these stereoisomers areidentical except that they are mirror images of one another. A specificstereoisomer may also be referred to as an enantiomer, and a mixture ofsuch isomers is often called an enantiomeric mixture. A 50:50 mixture ofenantiomers is referred to as a racemic mixture or a racemate, which mayoccur where there has been no stereoselection or stereospecificity in achemical reaction or process. The terms “racemic mixture” and “racemate”refer to an equimolar mixture of two enantiomeric species, devoid ofoptical activity.

The term “tautomer” or “tautomeric form” refers to structural isomers ofdifferent energies which are interconvertible via a low energy barrier.For example, proton tautomers (also known as prototropic tautomers)include interconversions via migration of a proton, such as keto-enoland imine-enamine isomerizations. Valence tautomers includeinterconversions by reorganization of some of the bonding electrons.

The term “prodrug” as used in this application refers to a precursor orderivative form of a compound of the invention that is capable of beingenzymatically or hydrolytically activated or converted into the moreactive parent form. See, e.g., Wilman, “Prodrugs in Cancer Chemotherapy”Biochemical Society Transactions, 14, pp. 375-382, 615th Meeting Belfast(1986) and Stella et al., “Prodrugs: A Chemical Approach to TargetedDrug Delivery,” Directed Drug Delivery, Borchardt et al., (ed.), pp.247-267, Humana Press (1985). The prodrugs of this invention include,but are not limited to, ester-containing prodrugs, phosphate-containingprodrugs, thiophosphate-containing prodrugs, sulfate-containingprodrugs, peptide-containing prodrugs, D-amino acid-modified prodrugs,glycosylated prodrugs, β-lactam-containing prodrugs, optionallysubstituted phenoxyacetamide-containing prodrugs, optionally substitutedphenylacetamide-containing prodrugs, 5-fluorocytosine and other5-fluorouridine prodrugs which can be converted into the more activecytotoxic free drug. Examples of cytotoxic drugs that can be derivatizedinto a prodrug form for use in this invention include, but are notlimited to, compounds of the invention and chemotherapeutic agents suchas described above.

The term “prodrug” is also meant to include a derivative of a compoundthat can hydrolyze, oxidize, or otherwise react under biologicalconditions (in vitro or in vivo) to provide a compound of thisinvention. Prodrugs may only become active upon such reaction underbiological conditions, or they may have activity in their unreactedforms. Examples of prodrugs contemplated in this invention include, butare not limited to, analogs or derivatives of compounds of any one ofthe formulae disclosed herein that comprise biohydrolyzable moietiessuch as biohydrolyzable amides, biohydrolyzable esters, biohydrolyzablecarbamates, biohydrolyzable carbonates, biohydrolyzable ureides, andbiohydrolyzable phosphate analogues. Other examples of prodrugs includederivatives of compounds of any one of the formulae disclosed hereinthat comprise —NO, —NO₂, —ONO, or —ONO₂ moieties. Prodrugs can typicallybe prepared using well-known methods, such as those described byBurger's Medicinal Chemistry and Drug Discovery (1995) 172-178, 949-982(Manfred E. Wolff ed., 5th ed); see also Goodman and Gilman's, ThePharmacological basis of Therapeutics, 8th ed., McGraw-Hill, Int. Ed.1992, “Biotransformation of Drugs.”

One preferred form of prodrug of the invention includes compounds (withor without any linker groups) and conjugates of the invention comprisingan adduct formed between an imine bond of the compounds/conjugates andan imine reactive reagent. Another preferred form of prodrug of theinvention includes compounds such as those of formula (I)-(IV), whereinwhen the double line

between N and C represents a single bond, X is H or an amine protectinggroup, and the compound becomes a prodrug. A prodrug of the inventionmay contain one or both forms of prodrugs described herein (e.g.,containing an adduct formed between an imine bond of thecompounds/conjugates and an imine reactive reagent, and/or containing aY leaving group when X is —H).

The term “imine reactive reagent” refers to a reagent that is capable ofreacting with an imine group. Examples of imine reactive reagentincludes, but is not limited to, sulfites (H₂SO₃, H₂SO₂ or a salt ofHSO₃ ⁻, SO₃ ²⁻ or HSO₂ ⁻ formed with a cation), metabisulfite (H₂S₂O₅ ora salt of S₂O₅ ²⁻ formed with a cation), mono, di, tri, andtetra-thiophosphates (PO₃SH₃, PO₂S₂H₃, POS₃H₃, PS₄H₃ or a salt ofPO₃S³⁻, PO₂S₂ ³⁻, POS₃ ³⁻ or PS₄ ³⁻ formed with a cation), thiophosphate esters ((R^(i)O)₂PS(OR^(i)), R^(i)SH, R^(i)SOH, R^(i)SO₂H,R^(i)SO₃H), various amines (hydroxyl amine (e.g., NH₂OH), hydrazine(e.g., NH₂NH₂), NH₂O—R^(i), R^(i)′NH—R^(i), NH₂—R^(i)), NH₂—CO—NH₂,NH₂—C(═S)—NH₂, thiosulfate (H₂S₂O₃ or a salt of S₂O₃ ²⁻ formed with acation), dithionite (H₂S₂O₄ or a salt of S₂O₄ ²⁻ formed with a cation),phosphorodithioate (P(═S)(OR^(k))(SH)(OH) or a salt thereof formed witha cation), hydroxamic acid (R^(k)C(═O)NHOH or a salt formed with acation), hydrazide (R^(k)CONHNH₂), formaldehyde sulfoxylate (HOCH₂SO₂Hor a salt of HOCH₂SO₂ ⁻ formed with a cation, such as HOCH₂SO₂ ⁻Na⁺),glycated nucleotide (such as GDP-mannose), fludarabine or a mixturethereof, wherein R^(i) and R^(i′) are each independently a linear orbranched alkyl having 1 to 10 carbon atoms and are substituted with atleast one substituent selected from —N(R^(j))₂, —CO₂H, —SO₃H, and —PO₃H;R^(i) and R^(i′) can be further optionally substituted with asubstituent for an alkyl described herein; R^(j) is a linear or branchedalkyl having 1 to 6 carbon atoms; and R^(k) is a linear, branched orcyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms, aryl,heterocyclyl or heteroaryl (preferably, R^(k) is a linear or branchedalkyl having 1 to 4 carbon atoms; more preferably, R^(k) is methyl,ethyl or propyl). Preferably, the cation is a monovalent cation, such asNa⁺ or K⁺. Preferably, the imine reactive reagent is selected fromsulfites, hydroxyl amine, urea and hydrazine. More preferably, the iminereactive reagent is NaHSO₃ or KHSO₃.

As used herein and unless otherwise indicated, the terms“biohydrolyzable amide,” “biohydrolyzable ester,” “biohydrolyzablecarbamate,” “biohydrolyzable carbonate,” “biohydrolyzable ureide” and“biohydrolyzable phosphate analogue” mean an amide, ester, carbamate,carbonate, ureide, or phosphate analogue, respectively, that either: 1)does not destroy the biological activity of the compound and confersupon that compound advantageous properties in vivo, such as uptake,duration of action, or onset of action; or 2) is itself biologicallyinactive but is converted in vivo to a biologically active compound.Examples of biohydrolyzable amides include, but are not limited to,lower alkyl amides, α-amino acid amides, alkoxyacyl amides, andalkylaminoalkylcarbonyl amides. Examples of biohydrolyzable estersinclude, but are not limited to, lower alkyl esters, alkoxyacyloxyesters, alkyl acylamino alkyl esters, and choline esters. Examples ofbiohydrolyzable carbamates include, but are not limited to, loweralkylamines, substituted ethylenediamines, amino acids,hydroxyalkylamines, heterocyclic and heteroaromatic amines, andpolyether amines. Particularly favored prodrugs and prodrug salts arethose that increase the bioavailability of the compounds of thisinvention when such compounds are administered to a mammal.

The phrase “pharmaceutically acceptable salt” as used herein, refers topharmaceutically acceptable organic or inorganic salts of a compound ofthe invention. Exemplary salts include, but are not limited, to sulfate,citrate, acetate, oxalate, chloride, bromide, iodide, nitrate,bisulfate, phosphate, acid phosphate, isonicotinate, lactate,salicylate, acid citrate, tartrate, oleate, tannate, pantothenate,bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate,gluconate, glucuronate, saccharate, formate, benzoate, glutamate,methanesulfonate “mesylate,” ethanesulfonate, benzenesulfonate,p-toluenesulfonate, pamoate (i.e.,1,1′-methylene-bis-(2-hydroxy-3-naphthoate)) salts, alkali metal (e.g.,sodium and potassium) salts, alkaline earth metal (e.g., magnesium)salts, and ammonium salts. A pharmaceutically acceptable salt mayinvolve the inclusion of another molecule such as an acetate ion, asuccinate ion or other counter ion. The counter ion may be any organicor inorganic moiety that stabilizes the charge on the parent compound.Furthermore, a pharmaceutically acceptable salt may have more than onecharged atom in its structure. Instances where multiple charged atomsare part of the pharmaceutically acceptable salt can have multiplecounter ions. Hence, a pharmaceutically acceptable salt can have one ormore charged atoms and/or one or more counter ion.

If the compound of the invention is a base, the desired pharmaceuticallyacceptable salt may be prepared by any suitable method available in theart, for example, treatment of the free base with an inorganic acid,such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid,methanesulfonic acid, phosphoric acid and the like, or with an organicacid, such as acetic acid, maleic acid, succinic acid, mandelic acid,fumaric acid, malonic acid, pyruvic acid, oxalic acid, glycolic acid,salicylic acid, a pyranosidyl acid, such as glucuronic acid orgalacturonic acid, an alpha hydroxy acid, such as citric acid ortartaric acid, an amino acid, such as aspartic acid or glutamic acid, anaromatic acid, such as benzoic acid or cinnamic acid, a sulfonic acid,such as p-toluenesulfonic acid or ethanesulfonic acid, or the like.

If the compound of the invention is an acid, the desiredpharmaceutically acceptable salt may be prepared by any suitable method,for example, treatment of the free acid with an inorganic or organicbase, such as an amine (primary, secondary or tertiary), an alkali metalhydroxide or alkaline earth metal hydroxide, or the like. Illustrativeexamples of suitable salts include, but are not limited to, organicsalts derived from amino acids, such as glycine and arginine, ammonia,primary, secondary, and tertiary amines, and cyclic amines, such aspiperidine, morpholine and piperazine, and inorganic salts derived fromsodium, calcium, potassium, magnesium, manganese, iron, copper, zinc,aluminum and lithium.

As used herein, the term “solvate” means a compound which furtherincludes a stoichiometric or non-stoichiometric amount of solvent suchas water, isopropanol, acetone, ethanol, methanol, DMSO, ethyl acetate,acetic acid, and ethanolamine dichloromethane, 2-propanol, or the like,bound by non-covalent intermolecular forces. Solvates or hydrates of thecompounds are readily prepared by addition of at least one molarequivalent of a hydroxylic solvent such as methanol, ethanol,1-propanol, 2-propanol or water to the compound to result in solvationor hydration of the imine moiety.

The terms “abnormal cell growth” and “proliferative disorder” are usedinterchangeably in this application. “Abnormal cell growth,” as usedherein, unless otherwise indicated, refers to cell growth that isindependent of normal regulatory mechanisms (e.g., loss of contactinhibition). This includes, for example, the abnormal growth of: (1)tumor cells (tumors) that proliferate by expressing a mutated tyrosinekinase or overexpression of a receptor tyrosine kinase; (2) benign andmalignant cells of other proliferative diseases in which aberranttyrosine kinase activation occurs; (3) any tumors that proliferate byreceptor tyrosine kinases; (4) any tumors that proliferate by aberrantserine/threonine kinase activation; and (5) benign and malignant cellsof other proliferative diseases in which aberrant serine/threoninekinase activation occurs.

The terms “cancer” and “cancerous” refer to or describe thephysiological condition in mammals that is typically characterized byunregulated cell growth. A “tumor” comprises one or more cancerouscells, and/or benign or pre-cancerous cells.

A “therapeutic agent” encompasses both a biological agent such as anantibody, a peptide, a protein, an enzyme or a chemotherapeutic agent.

A “chemotherapeutic agent” is a chemical compound useful in thetreatment of cancer.

A “metabolite” is a product produced through metabolism in the body of aspecified compound, a derivative thereof, or a conjugate thereof, orsalt thereof. Metabolites of a compound, a derivative thereof, or aconjugate thereof, may be identified using routine techniques known inthe art and their activities determined using tests such as thosedescribed herein. Such products may result for example from theoxidation, hydroxylation, reduction, hydrolysis, amidation, deamidation,esterification, deesterification, enzymatic cleavage, and the like, ofthe administered compound. Accordingly, the invention includesmetabolites of compounds, a derivative thereof, or a conjugate thereof,of the invention, including compounds, a derivative thereof, or aconjugate thereof, produced by a process comprising contacting acompound, a derivative thereof, or a conjugate thereof, of thisinvention with a mammal for a period of time sufficient to yield ametabolic product thereof.

The phrase “pharmaceutically acceptable” indicates that the substance orcomposition must be compatible chemically and/or toxicologically, withthe other ingredients comprising a formulation, and/or the mammal beingtreated therewith.

The term “protecting group” or “protecting moiety” refers to asubstituent that is commonly employed to block or protect a particularfunctionality while reacting other functional groups on the compound, aderivative thereof, or a conjugate thereof. For example, an“amine-protecting group” or an “amino-protecting moiety” is asubstituent attached to an amino group that blocks or protects the aminofunctionality in the compound. Such groups are well known in the art(see for example P. Wuts and T. Greene, 2007, Protective Groups inOrganic Synthesis, Chapter 7, J. Wiley & Sons, NJ) and exemplified bycarbamates such as methyl and ethyl carbamate, FMOC, substituted ethylcarbamates, carbamates cleaved by 1,6-β-elimination (also termed “selfimmolative”), ureas, amides, peptides, alkyl and aryl derivatives.Suitable amino-protecting groups include acetyl, trifluoroacetyl,t-butoxycarbonyl (BOC), benzyloxycarbonyl (CBZ) and9-fluorenylmethylenoxycarbonyl (Fmoc). For a general description ofprotecting groups and their use, see P. G. M. Wuts & T. W. Greene,Protective Groups in Organic Synthesis, John Wiley & Sons, New York,2007.

The term “leaving group” refers to an group of charged or unchargedmoiety that departs during a substitution or displacement. Such leavinggroups are well known in the art and include, but not limited to,halogens, esters, alkoxy, hydroxyl, tosylates, triflates, mesylates,nitriles, azide, carbamate, disulfides, thioesters, thioethers anddiazonium compounds.

The term “bifunctional crosslinking agent,” “bifunctional linker” or“crosslinking agents” refers to modifying agents that possess tworeactive groups; one of which is capable of reacting with a cell bindingagent while the other one reacts with the cytotoxic compound to link thetwo moieties together. Such bifunctional crosslinkers are well known inthe art (see, for example, Isalm and Dent in Bioconjugation chapter 5, p218-363, Groves Dictionaries Inc. New York, 1999). For example,bifunctional crosslinking agents that enable linkage via a thioetherbond includeN-succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (SMCC) tointroduce maleimido groups, or withN-succinimidyl-4-(iodoacetyl)-aminobenzoate (SIAB) to introduceiodoacetyl groups. Other bifunctional crosslinking agents that introducemaleimido groups or haloacetyl groups on to a cell binding agent arewell known in the art (see US Patent Applications 2008/0050310,20050169933, available from Pierce Biotechnology Inc. P.O. Box 117,Rockland, Ill. 61105, USA) and include, but not limited to,bis-maleimidopolyethyleneglycol (BMPEO), BM(PEO)₂, BM(PEO)₃,N-(β-maleimidopropyloxy)succinimide ester (BMPS), γ-maleimidobutyricacid N-succinimidyl ester (GMBS), ε-maleimidocaproic acidN-hydroxysuccinimide ester (EMCS), 5-maleimidovaleric acid NHS, HBVS,N-succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxy-(6-amidocaproate),which is a “long chain” analog of SMCC (LC-SMCC),m-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS),4-(4-N-maleimidophenyl)-butyric acid hydrazide or HCl salt (MPBH),N-succinimidyl 3-(bromoacetamido)propionate (SBAP), N-succinimidyliodoacetate (SIA), κ-maleimidoundecanoic acid N-succinimidyl ester(KMUA), N-succinimidyl 4-(p-maleimidophenyl)-butyrate (SMPB),succinimidyl-6-(β-maleimidopropionamido)hexanoate (SMPH),succinimidyl-(4-vinylsulfonyl)benzoate (SVSB), dithiobis-maleimidoethane(DTME), 1,4-bis-maleimidobutane (BMB), 1,4bismaleimidyl-2,3-dihydroxybutane (BMDB), bis-maleimidohexane (BMH),bis-maleimidoethane (BMOE), sulfosuccinimidyl4-(N-maleimido-methyl)cyclohexane-1-carboxylate (sulfo-SMCC),sulfosuccinimidyl(4-iodo-acetyl)aminobenzoate (sulfo-SIAB),m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (sulfo-MBS),N-(γ-maleimidobutryloxy)sulfosuccinimde ester (sulfo-GMBS),N-(ε-maleimidocaproyloxy)sulfosuccimido ester (sulfo-EMCS),N-(κ-maleimidoundecanoyloxy)sulfosuccinimide ester (sulfo-KMUS), andsulfosuccinimidyl 4-(p-maleimidophenyl)butyrate (sulfo-SMPB).

Heterobifunctional crosslinking agents are bifunctional crosslinkingagents having two different reactive groups. Heterobifunctionalcrosslinking agents containing both an amine-reactiveN-hydroxysuccinimide group (NHS group) and a carbonyl-reactive hydrazinegroup can also be used to link the cytotoxic compounds described hereinwith a cell-binding agent (e.g., antibody). Examples of suchcommercially available heterobifunctional crosslinking agents includesuccinimidyl 6-hydrazinonicotinamide acetone hydrazone (SANH),succinimidyl 4-hydrazidoterephthalate hydrochloride (SHTH) andsuccinimidyl hydrazinium nicotinate hydrochloride (SHNH). Conjugatesbearing an acid-labile linkage can also be prepared using ahydrazine-bearing benzodiazepine derivative of the present invention.Examples of bifunctional crosslinking agents that can be used includesuccinimidyl-p-formyl benzoate (SFB) andsuccinimidyl-p-formylphenoxyacetate (SFPA).

Bifunctional crosslinking agents that enable the linkage of cell bindingagent with cytotoxic compounds via disulfide bonds are known in the artand include N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP),N-succinimidyl-4-(2-pyridyldithio)pentanoate (SPP),N-succinimidyl-4-(2-pyridyldithio)butanoate (SPDB),N-succinimidyl-4-(2-pyridyldithio)2-sulfo butanoate (sulfo-SPDB) tointroduce dithiopyridyl groups. Other bifunctional crosslinking agentsthat can be used to introduce disulfide groups are known in the art andare disclosed in U.S. Pat. Nos. 6,913,748, 6,716,821 and US PatentPublications 20090274713 and 20100129314, all of which are incorporatedherein by reference. Alternatively, crosslinking agents such as2-iminothiolane, homocysteine thiolactone or S-acetylsuccinic anhydridethat introduce thiol groups can also be used.

A “linker,” “linker moiety,” or “linking group” as defined herein refersto a moiety that connects two groups, such as a cell binding agent and acytotoxic compound, together. Typically, the linker is substantiallyinert under conditions for which the two groups it is connecting arelinked. A bifunctional crosslinking agent may comprise two reactivegroups, one at each ends of a linker moiety, such that one reactivegroup can be first reacted with the cytotoxic compound to provide acompound bearing the linker moiety and a second reactive group, whichcan then react with a cell binding agent. Alternatively, one end of thebifunctional crosslinking agent can be first reacted with the cellbinding agent to provide a cell binding agent bearing a linker moietyand a second reactive group, which can then react with a cytotoxiccompound. The linking moiety may contain a chemical bond that allows forthe release of the cytotoxic moiety at a particular site. Suitablechemical bonds are well known in the art and include disulfide bonds,thioether bonds, acid labile bonds, photolabile bonds, peptidase labilebonds and esterase labile bonds (see for example U.S. Pat. Nos.5,208,020; 5,475,092; 6,441,163; 6,716,821; 6,913,748; 7,276,497;7,276,499; 7,368,565; 7,388,026 and 7,414,073). Preferred are disulfidebonds, thioether and peptidase labile bonds. Other linkers that can beused in the present invention include non-cleavable linkers, such asthose described in are described in detail in U.S. publication number20050169933, or charged linkers or hydrophilic linkers and are describedin US 2009/0274713, US 2010/01293140 and WO 2009/134976, each of whichis expressly incorporated herein by reference, each of which isexpressly incorporated herein by reference.

In one embodiment, the linking group with a reactive group attached atone end,

-   such as a reactive ester, is selected from the following:-   —O(CR₂₀R₂₁)_(m)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —O(CR₂₀R₂₁)_(m)(CR₂₆═CR₂₇)_(m′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —O(CR₂₀R₂₁)_(m)(alkynyl)_(n′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —O(CR₂₀R₂₁)_(m)(piperazino)_(t′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —O(CR₂₀R₂₁)_(m)(pyrrolo)_(t′)(CR₂₂R₂₃)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —O(CR₂₀R₂₁)_(m)A″_(m″)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —S(CR₂₀R₂₁)_(m)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —S(CR₂₀R₂₁)_(m)(CR₂₆═CR₂₇)_(m′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —S(CR₂₀R₂₁)_(m)(alkynyl)_(n′)(CR₂₂R₂₃)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —S(CR₂₀R₂₁)_(m)(piperazino)_(t′)(CR₂₂R₂₃)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —S(CR₂₀R₂₁)_(m)(pyrrolo)_(t′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —S(CR₂₀R₂₁)_(m)A″_(m″)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —NR₃₃(C═O)_(p″)(CR₂₀R₂₁)_(m)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —NR₃₃(C═O)_(p″)(CR₂₀R₂₁)_(m)(CR₂₆═CR₂₇)_(m′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —NR₃₃(C═O)_(p″)(CR₂₀R₂₁)_(m)(alkynyl)_(n′)(CR₂₂R₂₃)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)    ⁻ (CO)_(t)X″,-   —NR₃₃(C═O)_(p″)(CR₂₀R₂₁)_(m)(piperazino)_(t′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —NR₃₃(C═O)_(p″)(CR₂₀R₂₁)_(m)(pyrrolo)_(t′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)    ⁻(CO)_(t)X″,-   —NR₃₃(C═O)_(p″)(CR₂₀R₂₁)_(m)A″_(m″)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)(CR₂₆═CR₂₇)_(m′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)(alkynyl)_(n′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)(piperazino)_(t′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)A″_(m″)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)(CR₂₉═N—NR₃₀)_(n″)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)(CR₂₉═N—NR₃₀)_(n)(CR₂₆═CR₂₇)_(m′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)(CR₂₉═N—NR₃₀)_(n″)(alkynyl)_(n′)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)    ⁻(CO)_(t)X″,-   —(CR₂₀R₂₁)_(m)(CR₂₉═NNR₃₀)_(n″)A″_(m″)(CR₂₂R₂₃)_(n)(OCH₂CH₂)_(p)(CR₄₀R₄₁)_(p″)Y″(CR₂₄R₂₅)_(q)(CO)_(t)X″,    wherein:    -   m, n, p, q, m′, n′, t′ are integer from 1 to 10, or are        optionally 0;    -   t, m″, n″, and p″ are 0 or 1;    -   X″ is selected from OR₃₆, SR₃₇, NR₃₈R₃₉, wherein R₃₆, R₃₇, R₃₈,        R₃₉ are H, or linear, branched or cyclic alkyl, alkenyl or        alkynyl having from 1 to 20 carbon atoms and, or, a polyethylene        glycol unit —(OCH₂CH₂)_(n), R₃₇, optionally, is a thiol        protecting group when t=1, COX″ forms a reactive ester selected        from N-hydroxysuccinimide esters, N-hydroxyphthalimide esters,        N-hydroxy sulfo-succinimide esters, para-nitrophenyl esters,        dinitrophenyl esters, pentafluorophenyl esters and their        derivatives, wherein said derivatives facilitate amide bond        formation;    -   Y″ is absent or is selected from O, S, S—S or NR₃₂, wherein R₃₂        has the same definition as given above for R; or    -   when Y″ is not S—S and t=0, X″ is selected from a maleimido        group, a haloacetyl group or SR₃₇, wherein R₃₇ has the same        definition as above;    -   A″ is an amino acid residue or a polypeptide containing between        2 to 20 amino acid residues;    -   R₂₀, R₂₁, R₂₂, R₂₃, R₂₄, R₂₅, R₂₆, and R₂₇ are the same or        different, and are —H or a linear or branched alkyl having from        1 to 5 carbon atoms;    -   R₂₉ and R₃₀ are the same or different, and are —H or alkyl from        1 to 5 carbon atoms;    -   R₃₃ is —H or linear, branched or cyclic alkyl, alkenyl or        alkynyl having from 1 to 12 carbon atoms, a polyethylene glycol        unit R—(OCH₂CH₂)_(n)—, or R₃₃ is —COR₃₄, —CSR₃₄, —SOR₃₄, or        —SO₂R₃₄, wherein R₃₄ is H or linear, branched or cyclic alkyl,        alkenyl or alkynyl having from 1 to 20 carbon atoms or, a        polyethylene glycol unit —(OCH₂CH₂)_(n); and    -   one of R₄₀ and R₄₁ is optionally a negatively or positively        charged functional group and the other is H or alkyl, alkenyl,        alkynyl having 1 to 4 carbon atoms.

Any of the above linking groups may be present in any of the compounds,drug-linker compounds, or conjugates of the invention, includingreplacing the linking groups of any of the formulas described herein.

The term “amino acid” refers to naturally occurring amino acids ornon-naturally occurring amino acid. In one embodiment, the amino acid isrepresented by NH₂—C(R^(aa′)R^(aa))—C(═O)OH, wherein R^(aa) and R^(aa′)are each independently H, an optionally substituted linear, branched orcyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms, aryl,heteroaryl or heterocyclyl, or R^(aa) and the N-terminal nitrogen atomcan together form a heterocyclic ring (e.g., as in proline). The term“amino acid residue” refers to the corresponding residue when onehydrogen atom is removed from the amine and/or carboxy end of the aminoacid, such as —NH—C(R^(aa′)R^(aa))—C(═O)O—.

The term “cation” refers to an ion with positive charge. The cation canbe monovalent (e.g., Na⁺, K⁺, etc.), bi-valent (e.g., Ca²⁺, Mg²⁺, etc.)or multi-valent (e.g., Al³⁺ etc.). Preferably, the cation is monovalent.

The term “therapeutically effective amount” means that amount of activecompound or conjugate that elicits the desired biological response in asubject. Such response includes alleviation of the symptoms of thedisease or disorder being treated, prevention, inhibition or a delay inthe recurrence of symptom of the disease or of the disease itself, anincrease in the longevity of the subject compared with the absence ofthe treatment, or prevention, inhibition or delay in the progression ofsymptom of the disease or of the disease itself. Determination of theeffective amount is well within the capability of those skilled in theart, especially in light of the detailed disclosure provided herein.Toxicity and therapeutic efficacy of compound I can be determined bystandard pharmaceutical procedures in cell cultures and in experimentalanimals. The effective amount of compound or conjugate of the presentinvention or other therapeutic agent to be administered to a subjectwill depend on the stage, category and status of the multiple myelomaand characteristics of the subject, such as general health, age, sex,body weight and drug tolerance. The effective amount of compound orconjugate of the present invention or other therapeutic agent to beadministered will also depend on administration route and dosage form.Dosage amount and interval can be adjusted individually to provideplasma levels of the active compound that are sufficient to maintaindesired therapeutic effects.

Cytotoxic Compounds

In a first embodiment, the present invention is directed to cytotoxiccompounds described herein (e.g., compounds of structural formula (I),(II), (III), (IV), (V) or (VI), or a pharmaceutically acceptable saltthereof). In certain embodiments, the cytotoxic compound is representedby structural formula (I) or a pharmaceutically acceptable salt thereof.

In certain embodiments, for structural formulas (I), (II), (III), (IV),(V) and (VI), one of L′, L″ and L′″ is represented by formula (A), andthe others are each independently —H, an linear or branched alkyl havingfrom 1 to 6 carbon atoms, halogen, —OH, (C₁-C₆)alkoxy, or —NO₂.Specifically, one of L′, L″ and L′″ is represented by formula (A), andthe others are —H.

In a 1^(st) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), L′ is represented by formula (A) and L″ andL′″ are both —H; and the remaining variables are as described above inthe first embodiment.

In a 2^(nd) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), R_(x) is a linear, branched or cyclic alkylhaving 1 to 6 carbon atoms optionally substituted with halogen, —OH,(C₁-C₃)alkyl, (C₁-C₃)alkoxy, halo(C₁-C₃)alkyl, or a charged substituentor an ionizable group Q; and the remaining variables are as describedabove in the first embodiment or the 1^(st) specific embodiment.

In certain embodiments, Q is i) —SO₃H, —Z′—SO₃H, —OPO₃H₂, —Z′—OPO₃H₂,—PO₃H₂, —Z′—PO₃H₂, —CO₂H, —Z′—CO₂H, —NR₁₁R₁₂, or —Z′—NR₁₁R₁₂, or apharmaceutically acceptable salt thereof; or, ii) —N⁺R₁₄R₁₅R₁₆X⁻ or—Z′—N⁺R₁₄R₁₅R₁₆X⁻; Z′ is an optionally substituted alkylene, anoptionally substituted cycloalkylene or an optionally substitutedphenylene; R₁₄ to R₁₆ are each independently an optionally substitutedalkyl; and X⁻ is a pharmaceutically acceptable anion; and the remainingvariables are as described above in the 2^(nd) specific embodiment. Morespecifically, Q is —SO₃H or a pharmaceutically acceptable salt thereof.

In a 3^(rd) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), J is a moiety comprising a reactive groupselected from the group consisting of NHR^(c1), —COOH, and —COE, wherein—COE represents a reactive ester and R^(c1) is —H or linear or branchedalkyl having 1 to 4 carbon atoms optionally substituted with halogen,—OH or (C₁-C₃)alkoxy; and the remaining variables are as described abovein the first embodiment or the 1^(st) or 2^(nd) specific embodiment.

In certain embodiments, J is COE selected from N-hydroxysuccinimdeester, N-hydroxy sulfosuccinimide ester, nitrophenyl (e.g., 2 or4-nitrophenyl) ester, dinitrophenyl (e.g., 2,4-dinitrophenyl) ester,sulfo-tetraflurophenyl (e.g., 4-sulfo-2,3,5,6-tetrafluorophenyl) ester,and pentafluorophenyl ester; and the remaining variables are asdescribed above in the 3^(rd) specific embodiment. More specifically,COE is a N-hydroxysuccinimide ester.

In a 4^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), L′ is represented by the following formula:

—NR₅—P—C(═O)—(CR_(a)R_(b))_(m)-J  (B1);

—NR₅—P—C(═O)—Cy-(CR_(a)R_(b))_(m′)-J  (B2);

—C(═O)—P—NR₅—(CR_(a)R_(b))_(m)-J  (C1); or

—C(═O)—P—NR₅—Cy-(CR_(a)R_(b))_(m′)-J  (C2),

wherein:

-   -   J is —COE;    -   R_(a) and R_(b), for each occurrence, are each independently —H,        (C₁-C₃)alkyl or a charged substituent or an ionizable group Q;    -   m is an integer from 1 to 6;    -   m′ is 0 or an integer from 1 to 6;    -   Cy is a cyclic alkyl having 5 or 6 ring carbon atoms optionally        substituted with halogen, —OH, (C₁-C₃)alkyl, (C₁-C₃)alkoxy, or        halo(C₁-C₃)alkyl; and the remaining variables are as described        above in the first embodiment or the 1^(st), 2^(nd) or 3^(rd)        specific embodiment.

In certain embodiments, R_(a) and R_(b) are both H; Cy for formulas (B2)and (C2) is cyclohexane; and R₅ is H or Me; and the remaining variablesare as described above in the 4^(th) specific embodiment. Morespecifically, m′ in formulas (B2) and (C2) is 0 or 1.

In a 5^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), L′ is represented by the following formula:

—NR₅—P—C(═O)—(CR_(a)R_(b))_(m)—S—Z^(s)  (B3); or

—C(═O)—P—NR₅—(CR_(a)R_(b))_(m)—S—Z^(s)  (C3),

wherein:

-   -   R_(a) and R_(b), for each occurrence, are each independently —H,        (C₁-C₃)alkyl or a charged substituent or an ionizable group Q;    -   m is an integer from 1 to 6;    -   Z^(s) is —H, —SR^(d), —C(═O)R^(d1) or is selected from any one        of the following formulas:

wherein:

-   -   q is an integer fro 1 to 5;    -   n′ is an integer from 2 to 6;    -   M is a cation (e.g., H⁺, Na⁺ or K⁺);    -   R^(d) is a linear or branched alkyl having 1 to 6 carbon atoms        or selected from phenyl, nitrophenyl (e.g., 2 or 4-nitrophenyl),        dinitrophenyl (e.g., 2,4-dinitrophenyl), carboxynitrophenyl        (e.g., 3-carboxy-4-nitrophenyl), pyridyl or nitropyridyl (e.g.,        4-nitropyridyl);    -   R^(d1) is a linear or branched alkyl having 1 to 6 carbon atoms;        and the remaining variables are as described above in the first        embodiment or the 1^(st), 2^(nd), 3^(rd) or 4^(th) specific        embodiment.

In one embodiment, Z^(s) is —H. In another embodiment, Z^(s) is —SMe or—SPy (Py is a pyridyl).

In yet another embodiment, Z^(s) is selected from any one of thefollowing formulas:

wherein U is —H or —SO₃M; and the remaining variables are as describedabove for formulas (a1′)-(a15′).

In certain embodiments, the charged substituent or an ionizable group Qis i) —SO₃H, —Z′—SO₃H, —OPO₃H₂, —Z′—OPO₃H₂, —PO₃H₂, —Z′—PO₃H₂, —CO₂H,—Z′—CO₂H, —NR₁₁R₁₂, or —Z′—NR₁₁R₁₂, or a pharmaceutically acceptablesalt thereof; or, ii) —N⁺R₁₄R₁₅R₁₆X⁻ or —Z′—N⁺R₁₄R₁₅R₁₆X⁻; Z′ is anoptionally substituted alkylene, an optionally substituted cycloalkyleneor an optionally substituted phenylene; R₁₄ to R₁₆ are eachindependently an optionally substituted alkyl; and X⁻ is apharmaceutically acceptable anion; and the remaining variables are asdescribed above in the 5^(th) specific embodiment. More specifically, Qis —SO₃H or a pharmaceutically acceptable salt thereof.

In certain embodiments, R_(a) and R_(b) are both —H and R₅ is H or Me;and the remaining variables are as described above in the 5^(th)specific embodiment.

In certain embodiments, —(CR_(a)R_(b))_(m)— is —(CH₂)_(m″)—C(Me₂)- andm″ is an integer from 1 to 5; the remaining variables are as describedabove in the 5^(th) specific embodiment.

In a 6^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), P is a peptide containing 2 to 10 amino acidresidues; and the remaining variables are as described above in thefirst embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th) or 5^(th)specific embodiment.

In certain embodiments, P is a peptide containing 2 to 5 amino acidresidues; and the remaining variables are as described above in the6^(th) specific embodiment.

In certain embodiments, P is selected from Gly-Gly-Gly, Ala-Val,Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit, Leu-Cit,Lle-Cit, Trp, Cit, Phe-Ala, Phe-N⁹-tosyl-Arg, Phe-N⁹-nitro-Arg,Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu,Val-Ala-Val, Ala-Leu-Ala-Leu, β-Ala-Leu-Ala-Leu and Gly-Phe-Leu-Gly,Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit,D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg,D-Arg-D-Arg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met, andMet-Ala; and the remaining variables are as described above in the6^(th) specific embodiment.

In certain embodiments, P is Gly-Gly-Gly, Ala-Val, Ala-Ala, Ala-D-Ala,D-Ala-Ala, and D-Ala-D-Ala; and the remaining variables are as describedabove in the 6^(th) specific embodiment.

In a 7^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), the double line

between N and C represents a double bond; and the remaining variablesare as described above in the first embodiment, or the 1^(st), 2^(nd),3^(rd), 4^(th), 5^(th) or 6^(th) specific embodiment.

In a 8^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), the double line

between N and C represents a single bond, X is —H or an amine protectinggroup; and Y is selected from —H, —OR, —OCOR′, —SR, —NR′R″, anoptionally substituted 5- or 6-membered nitrogen-containing heterocycle,—SO₃H, —SO₂H and —OSO₃H; and the remaining variables are as described inthe first embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th),6^(th) or 7^(th) specific embodiment.

In certain embodiments, Y is selected from —H, —SO₃M, —OH, —OMe, —OEt or—NHOH, wherein M is —H, Na⁺ or K⁺; and the remaining variables are asdescribed above in the 8^(th) specific embodiment. More specifically, Yis —H, —SO₃M or —OH.

In a 9^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), X′ is selected from the group consisting of—H, —OH, an optionally substituted linear, branched or cyclic alkyl,alkenyl or alkynyl having from 1 to 10 carbon atoms, and phenyl; and theremaining variables are as described in the first embodiment or the1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th), 7^(th) or 8^(th)specific embodiment.

In certain embodiments, X′ is —H, —OH, (C₁-C₃)alkyl, halo(C₁-C₃)alkyl,or phenyl; and the remaining variables are as described above in the9^(th) specific embodiment. More specifically, X′ is —H, —OH or -Me.Even more specifically, X′ is —H.

In a 10^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), Y′ is —H, an oxo group, (C₁-C₃)alkyl orhalo(C₁-C₃)alkyl; and the remaining variables are as described in thefirst embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th),7^(th) 8^(th) or 9^(th) specific embodiment. More specifically, Y′ is —Hor oxo. Even more specifically, Y′ is —H.

In a 11^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), A and A′ are the same or different, and areselected from —O—, —S—, —NR₅—, and oxo —(C═O)—; and the remainingvariables are as described in the first embodiment or the 1^(st),2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th), 7^(th) 8^(th), 9^(th) or 10^(th)specific embodiment. More specifically, A and A′ are the same ordifferent, and are selected from —O— and —S—. Even more specifically, Aand A′ are —O—.

In a 12^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), R₆ is —OMe; and the remaining variables areas described in the first embodiment or the 1^(st), 2^(nd), 3^(rd),4^(th), 5^(th), 6^(th), 7^(th), 9^(th), 10^(th) or 11^(th) specificembodiment.

In a 13^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ areindependently-H, halogen, —NO₂, —OH, (C₁-C₃)alkyl, halo(C₁-C₃)alkyl or(C₁-C₃)alkoxy; and the remaining variables are as described in the firstembodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th) 7^(th),8^(th), 9^(th), 10^(th), 11^(th) or 12^(th) specific embodiment. Morespecifically, R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ are all —H.

In a 14^(th) specific embodiment, for structural formulas (I), (II),(III), (IV), (V) and (VI), R, R′, R″ and R₅ are each independently —H or(C₁-C₃)alkyl; and the remaining variables are as described in the firstembodiment or the 1^(st), 2^(nd) 3^(rd), 4^(th), 5^(th), 6^(th), 7^(th),8^(th), 9^(th), 10^(th), 11^(th), 12^(th) or 13^(th) specificembodiment.

In a 15^(th) specific embodiments, for structural formulas (I), (II),(III), (IV), (V) and (VI), the double line

between N and C represents a single bond or double bond, provided thatwhen it is a double bond X is absent and Y is —H, and when it is asingle bond, X is —H, Y is —OH or —SO₃M;

-   -   R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ are all —H;    -   R₆ is —OMe;    -   X′ and Y′ are both —H;    -   A and A′ are —O—;    -   M is H, Na⁺ or K⁺; and the remaining variables are as described        in the first embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th),        5^(th) or 6^(th) specific embodiment.

In a 16^(th) specific embodiment, the cytotoxic compound of the presentinvention is selected from the following formulas:

or a pharmaceutically acceptable salt thereof, wherein:

-   -   R₁₀₀ is —OH, —OMe or

-   -   Y is —H, —OH or —SO₃M; and    -   M is a pharmaceutically acceptable cation (e.g., H⁺, Na⁺ or K⁺);    -   Z^(s) is —H, —SR^(d), —C(═O)R^(d1) or is selected from formulas        (a1′)-(a15′) described above.

In a specific embodiment, Z^(s) is selected from formulas (a1)-(a15)described above.

In a more specific embodiment, Z^(s) is selected from formulas (a7),(a8), (a9) and (a15). In a even more specific embodiment, Z^(s) isrepresented by formula (a9). Alternatively, Z^(s) is represented byformula (a7).

In another specific embodiment, Z^(s) is —H.

In another specific embodiment, Y is —SO₃M. Alternatively, Y is —OH.

Also included in the present invention is metabolites of any cytotoxiccompounds or cell-binding agent-cytotoxic agent conjugates describedherein.

Synthesis of Cytotoxic Compounds

The cytotoxic compounds of the present invention can be preparedaccording to methods described in U.S. Pat. No. 8,765,740 and U.S.Application Publication No. 2012/0238731.

Representative processes for preparing the cytotoxic dimer compounds ofthe present invention are shown in Examples 1-10.

Cell-Binding Agents

The effectiveness of the conjugates of the invention as therapeuticagents depends on the careful selection of an appropriate cell-bindingagent. Cell-binding agents can be of any kind presently known, or thatbecome known, including peptides and non-peptides. Generally, these canbe antibodies (such as polyclonal antibodies and monoclonal antibodies,especially monoclonal antibodies), lymphokines, hormones, growthfactors, vitamins (such as folate etc., which can bind to a cell surfacereceptor thereof, e.g., a folate receptor), nutrient-transport molecules(such as transferrin), or any other cell-binding molecule or substance.

Selection of the appropriate cell-binding agent is a matter of choicethat partly depends upon the particular cell population that is to betargeted, but in many (but not all) cases, human monoclonal antibodiesare a good choice if an appropriate one is available. For example, themonoclonal antibody MY9 is a murine IgG₁ antibody that bindsspecifically to the CD33 Antigen (J. D. Griffin et al., Leukemia Res.,8:521 (1984)), and can be used if the target cells express CD33 as inthe disease of acute myelogenous leukemia (AML).

In certain embodiments, the cell-binding agent is not a protein. Forexample, in certain embodiments, the cell binding agent may be a vitaminthat binds to a vitamin receptor, such as a cell-surface receptor. Inthis regard, vitamin A binds to retinol-binding protein (RBP) to form acomplex, which complex in turn binds the STRA6 receptor with highaffinity and increases vitamin A in-take. In another example, folicacid/folate/vitamin B₉ binds the cell-surface folate receptor (FR), forexample, FRα, with high affinity. Folic acid or antibodies that bind toFRα can be used to target the folate receptor expressed on ovarian andother tumors. In addition, vitamin D and its analog bind to vitamin Dreceptor.

In other embodiments, the cell-binding agent is a protein or apolypeptide, or a compound comprising a protein or polypeptide,including antibody, non-antibody protein, or polypeptide. Preferably,the protein or polypeptides comprise one or more Lys residues with sidechain —NH₂ group. The Lys side chain —NH₂ groups can be covalentlylinked to the bifunctional crosslinkers, which in turn are linked to thedimer compounds of the invention, thus conjugating the cell-bindingagents to the dimer compounds of the invention. Each protein-basedcell-binding agents can contain multiple Lys side chain —NH₂ groupsavailable for linking the compounds of the invention through thebifunctional crosslinkers.

In one embodiment, GM-CSF, a ligand/growth factor which binds to myeloidcells can be used as a cell-binding agent to diseased cells from acutemyelogenous leukemia. IL-2 which binds to activated T-cells can be usedfor prevention of transplant graft rejection, for therapy and preventionof graft-versus-host disease, and for treatment of acute T-cellleukemia. MSH, which binds to melanocytes, can be used for the treatmentof melanoma, as can antibodies directed towards melanomas. Epidermalgrowth factor can be used to target squamous cancers, such as lung andhead and neck. Somatostatin can be used to target neuroblastomas andother tumor types. Estrogen (or estrogen analogues) can be used totarget breast cancer. Androgen (or androgen analogues) can be used totarget testes.

In certain embodiments, the cell-binding agent can be a lymphokine, ahormone, a growth factor, a colony stimulating factor, or anutrient-transport molecule.

In certain embodiments, the cell-binding agent is an antibody mimetic,such as an ankyrin repeat protein, a Centyrin, or an adnectin/monobody.

In other embodiments, the cell-binding agent is an antibody, a singlechain antibody, an antibody fragment that specifically binds to thetarget cell, a monoclonal antibody, a single chain monoclonal antibody,a monoclonal antibody fragment (or “antigen-binding portion”) thatspecifically binds to a target cell, a chimeric antibody, a chimericantibody fragment (or “antigen-binding portion”) that specifically bindsto the target cell, a domain antibody (e.g., sdAb), or a domain antibodyfragment that specifically binds to the target cell.

In certain embodiments, the cell-binding agent is a humanized antibody,a humanized single chain antibody, or a humanized antibody fragment (or“antigen-binding portion”). In a specific embodiment, the humanizedantibody is huMy9-6 or another related antibody, which is described inU.S. Pat. Nos. 7,342,110 and 7,557,189. In another specific embodiment,the humanized antibody is an anti-folate receptor antibody described inU.S. Provisional Application Nos. 61/307,797, 61/346,595, and 61/413,172and U.S. application Ser. No. 13/033,723 (published as US 2012/0009181A1). The teachings of all these applications are incorporated herein byreference in its entirety.

In certain embodiments, the cell-binding agent is a resurfaced antibody,a resurfaced single chain antibody, a resurfaced antibody fragment (or“antigen-binding portion”), or a bispecific antibody.

In certain embodiments, the cell-binding agent is a minibody, anavibody, a diabody, a tribody, a tetrabody, a nanobody, a probody, adomain antibody, or an unibody.

In other words, an exemplary cell binding agent may include an antibody,a single chain antibody, an antibody fragment that specifically binds tothe target cell, a monoclonal antibody, a single chain monoclonalantibody, a monoclonal antibody fragment that specifically binds to atarget cell, a chimeric antibody, a chimeric antibody fragment thatspecifically binds to the target cell, a bispecific antibody, a domainantibody, a domain antibody fragment that specifically binds to thetarget cell, an interferon (e.g., α, β, γ), a lymphokine (e.g., IL-2,IL-3, IL-4, and IL-6), a hormone (e.g., insulin, thyrotropin releasinghormone (TRH), melanocyte-stimulating hormone (MSH), and a steroidhormone (e.g., androgen and estrogen)), a vitamin (e.g., folate), agrowth factor (e.g., EGF, TGF-alpha, FGF, VEGF), a colony stimulatingfactor, a nutrient-transport molecule (e.g., transferrin; see O'Keefe etal. (1985) J. Biol. Chem. 260:932-937, incorporated herein byreference), a Centyrin (a protein scaffold based on a consensus sequenceof fibronectin type III (FN3) repeats; see U.S. Patent Publication2010/0255056, 2010/0216708 and 2011/0274623 incorporated herein byreference), an Ankyrin Repeat Protein (e.g., a designed ankyrin repeatprotein, known as DARPin; see U.S. Patent Publication Nos. 2004/0132028,2009/0082274, 2011/0118146, and 2011/0224100, incorporated herein byreference, and also see C. Zahnd et al., Cancer Res. (2010)70:1595-1605; Zahnd et al., J. Biol. Chem. (2006) 281(46):35167-35175;and Binz, H. K., Amstutz, P. & Pluckthun, A., Nature Biotechnology(2005) 23:1257-1268, incorporated herein by reference), an ankyrin-likerepeats protein or synthetic peptide (see e.g., U.S. Patent PublicationNo. 2007/0238667; U.S. Pat. No. 7,101,675; WO 2007/147213; and WO2007/062466, incorporated herein by reference), an Adnectin (afibronectin domain scaffold protein; see US Patent Publication Nos.2007/0082365; 2008/0139791, incorporated herein by reference), Avibody(including diabodies, triabodies, and tetrabodies; see U.S. PublicationNos. 2008/0152586 and 2012/0171115), dual receptor retargeting (DART)molecules (P. A. Moore et al., Blood, 2011; 117(17):4542-4551; Veri M C,et al., Arthritis Rheum, 2010 Mar. 30; 62(7):1933-43; Johnson S, et al.J Mol Biol, 2010 Apr. 9; 399(3):436-49), cell penetrating superchargedproteins (Methods in Enzymol. 502, 293-319 (2012), and othercell-binding molecules or substances.

In certain embodiments, the cell-binding agent may be a ligand thatbinds to a moiety on the target cell, such as a cell-surface receptor.For example, the ligand may be a growth factor or a fragment thereofthat binds to a growth factor receptor; or may be a cytokine or afragment thereof that binds to a cytokine receptor. In certainembodiments, the growth factor receptor or cytokine receptor is acell-surface receptor.

In certain embodiments, wherein the cell-binding agent is an antibody oran antigen-binding portion thereof (including antibody derivatives), orcertain antibody mimetics, the CBA may bind to a ligand on the targetcell, such as a cell-surface ligand, including cell-surface receptors.

Specific exemplary antigens or ligands may include renin; a growthhormone (e.g., human growth hormone and bovine growth hormone); a growthhormone releasing factor; a parathyroid hormone; a thyroid stimulatinghormone; a lipoprotein; alpha-1-antitrypsin; insulin A-chain; insulinB-chain; proinsulin; a follicle stimulating hormone; calcitonin; aluteinizing hormone; glucagon; a clotting factor (e.g., factor vmc,factor IX, tissue factor, and von Willebrands factor); an anti-clottingfactor (e.g., Protein C); an atrial natriuretic factor; a lungsurfactant; a plasminogen activator (e.g., a urokinase, a human urine ortissue-type plasminogen activator); bombesin; a thrombin; hemopoieticgrowth factor; tumor necrosis factor-alpha and -beta; an enkephalinase;RANTES (i.e., the regulated on activation normally T-cell expressed andsecreted); human macrophage inflammatory protein-1-alpha; a serumalbumin (human serum albumin); Muellerian-inhibiting substance; relaxinA-chain; relaxin B-chain; prorelaxin; a mouse gonadotropin-associatedpeptide; a microbial protein (beta-lactamase); DNase; IgE; a cytotoxicT-lymphocyte associated antigen (e.g., CTLA-4); inhibin; activin; avascular endothelial growth factor; a receptor for hormones or growthfactors; protein A or D; a rheumatoid factor; a neurotrophic factor(e.g., bone-derived neurotrophic factor, neurotrophin-3, -4, -5, or -6),a nerve growth factor (e.g., NGF-β); a platelet-derived growth factor; afibroblast growth factor (e.g., aFGF and bFGF); fibroblast growth factorreceptor 2; an epidermal growth factor; a transforming growth factor(e.g., TGF-alpha, TGF-β1, TGF-β2, TGF-β3, TGF-β4, and TGF-β5);insulin-like growth factor-I and -II; des(1-3)-IGF-I (brain IGF-I); aninsulin-like growth factor binding protein; melanotransferrin; EpCAM;GD3; FLT3; PSMA; PSCA; MUC1; MUC16; STEAP; CEA; TENB2; an EphA receptor;an EphB receptor; a folate receptor; FOLR1; mesothelin; cripto; analpha_(v)beta₆; integrins; VEGF; VEGFR; EGFR; transferrin receptor;IRTA1; IRTA2; IRTA3; IRTA4; IRTA5; CD proteins (e.g., CD2, CD3, CD4,CD5, CD6, CD8, CD11, CD14, CD19, CD20, CD21, CD22, CD25, CD26, CD28,CD30, CD33, CD36, CD37, CD38, CD40, CD44, CD52, CD55, CD56, CD59, CD70,CD79, CD80. CD81, CD103, CD105, CD123, CD134, CD137, CD138, and CD152),one or more tumor-associated antigens or cell-surface receptors (see USPublication No. 2008/0171040 or US Publication No. 2008/0305044,incorporated in their entirety by reference); erythropoietin; anosteoinductive factor; an immunotoxin; a bone morphogenetic protein; aninterferon (e.g., interferon-alpha, -beta, and -gamma); a colonystimulating factor (e.g., M-CSF, GM-CSF, and G-CSF); interleukins (e.g.,IL-1 to IL-10); a superoxide dismutase; a T-cell receptor; a surfacemembrane protein; a decay accelerating factor; a viral antigen s (e.g.,a portion of the HIV envelope); a transport protein, a homing receptor;an addressin; a regulatory protein; an integrin (e.g., CD11a, CD11b,CD11c, CD18, an ICAM, VLA-4, and VCAM); a tumor associated antigen(e.g., HER2, HER3 and HER4 receptor); endoglin; c-Met; c-kit; 1GF1R;PSGR; NGEP; PSMA; PSCA; TMEFF2; LGR5; B7H4; and fragments of any of theabove-listed polypeptides.

As used herein, the term “antibody” includes immunoglobulin (Ig)molecules. In certain embodiments, the antibody is a full-lengthantibody that comprises four polypeptide chains, namely two heavy chains(HC) and two light chains (LC) inter-connected by disulfide bonds. Eachheavy chain is comprised of a heavy chain variable region (HCVR or VH)and a heavy chain constant region (CH). The heavy chain constant regionis comprised of three domains, CH1, CH2, and CH3. Each light chain iscomprised of a light chain variable region (LCVR or VL) and a lightchain constant region, which is comprised of one domain, CL. The VH andVL regions can be further subdivided into regions of hypervariability,termed complementarity determining regions (CDRs). Interspersed withsuch regions are the more conserved framework regions (FRs). Each VH andVL is composed of three CDRs and four FRs, arranged from amino-terminusto carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3,CDR3, and FR4.

In certain embodiments, the antibody is IgG, IgA, IgE, IgD, or IgM. Incertain embodiments, the antibody is IgG1, IgG2, IgG3, or IgG4; or IgA1or IgA2.

In certain embodiments, the cell-binding agent is an “antigen-bindingportion” of a monoclonal antibody, sharing sequences critical forantigen-binding with an antibody (such as huMy9-6 or its relatedantibodies described in U.S. Pat. Nos. 7,342,110 and 7,557,189,incorporated herein by reference).

As used herein, the term “antigen-binding portion” of an antibody (orsometimes interchaneably referred to as “antibody fragments”), includeone or more fragments of an antibody that retain the ability tospecifically bind to an antigen. It has been shown that theantigen-binding function of an antibody can be performed by certainfragments of a full-length antibody. Examples of binding fragmentsencompassed within the term “antigen-binding portion” of an antibodyinclude (without limitation): (i) a Fab fragment, a monovalent fragmentconsisting of the VL, VH, CL and CH1 domains (e.g., an antibody digestedby papain yields three fragments: two antigen-binding Fab fragments, andone Fc fragment that does not bind antigen); (ii) a F(ab′)₂ fragment, abivalent fragment comprising two Fab fragments linked by a disulfidebridge at the hinge region (e.g., an antibody digested by pepsin yieldstwo fragments: a bivalent antigen-binding F(ab′)₂ fragment, and a pFc′fragment that does not bind antigen) and its related F(ab′) monovalentunit; (iii) a Fd fragment consisting of the VH and CH1 domains (i.e.,that portion of the heavy chain which is included in the Fab); (iv) a Fvfragment consisting of the VL and VH domains of a single arm of anantibody, and the related disulfide linked Fv; (v) a dAb (domainantibody) or sdAb (single domain antibody) fragment (Ward et al., Nature341:544-546, 1989), which consists of a VH domain; and (vi) an isolatedcomplementarity determining region (CDR). In certain embodiments, theantigen-binding portion is a sdAb (single domain antibody).

In certain embodiments, antigen-binding portion also include certainengineered or recombinant derivatives (or “derivative antibodies”) thatalso include one or more fragments of an antibody that retain theability to specifically bind to an antigen, in addition to elements orsequences that may not be found in naturally existing antibodies.

For example, although the two domains of the Fv fragment, VL and VH, arecoded for by separate genes, they can be joined, using standardrecombinant methods, by a synthetic linker that enables them to be madeas a single protein chain in which the VL and VH regions pair to formmonovalent molecules (known as single chain Fv (scFv); see, e.g., Birdet al. Science 242:423-426, 1988: and Huston et al., Proc. Natl. Acad.Sci. USA 85:5879-5883, 1988).

In all embodiments described herein, the N-terminus of an scFv may be aVH domain (i.e., N-VH-VL-C), or a VL domain (i.e., N-VL-VH-C).

Divalent (or bivalent) single-chain variable fragments (di-scFvs,bi-scFvs) can be engineered by linking two scFvs. This produces a singlepeptide chain with two VH and two VL regions, yielding a tandem scFvs(tascFv). More tandem repeats, such as tri-scFv, may be similarlyproduced by linking three or more scFv in a head-to-tail fashion.

In certain embodiments, scFvs may be linked through linker peptides thatare too short (about five amino acids) for the two variable regions tofold together, forcing scFvs to dimerize, and form diabodies (see, e.g.,Holliger et al., Proc. Natl. Acad. Sci. USA 90:6444-6448, 1993; Poljaket al., Structure 2:1121-1123, 1994). Diabodies may be bi-specific ormonospecific. Diabodies have been shown to have dissociation constantsup to 40-fold lower than corresponding scFvs, i.e., having a much higheraffinity to the target.

Still shorter linkers (one or two amino acids) lead to the formation oftrimers, or so-called triabodies or tribodies. Tetrabodies have alsobeen produced similarly. They exhibit an even higher affinity to theirtargets than diabodies. Diabodies, triabodies, and tetrabodies aresometimes collectively called “AVIBODY™” cell binding agents (or“AVIBODY” in short). That is, AVIBODY having two, three, or four TargetBinding Regions (TBRs) are commonly known as Dia-, Tria- andTetrabodies. See, for example, U.S. Publication Nos. 2008/0152586 and2012/0171115 for details, the entire teachings of which are incorporatedherein by reference.

All of these formats can be composed from variable fragments withspecificity for two or more different antigens, in which case they aretypes of bi- or multi-specific antibodies. For example, certainbispecific tandem di-scFvs, are known as bi-specific T-cell engagers(BiTEs).

In certain embodiments, each scFv in the tandem scFv ordiabody/triabody/tetrabody may have the same or different bindingspecificity, and each may independently have an N-terminal VH orN-terminal VL.

Single chain Fv (scFv) can also be fused to an Fc moiety, such as thehuman IgG Fc moiety to obtain IgG-like properties, but nevertheless theyare still encoded by a single gene. As transient production of suchscFv-Fc proteins in mammalians can easily achieve milligram amounts,this derivative antibody format is particularly suitable for manyresearch applications.

Fcabs are antibody fragments engineered from the Fc constant region ofan antibody. Fcabs can be expressed as soluble proteins, or they can beengineered back into a full-length antibody, such as IgG, to createmAb2. A mAb2 is a full-length antibody with an Fcab in place of thenormal Fc region. With these additional binding sites, mAb2 bispecificmonoclonal antibodies can bind two different targets at the same time.

In certain embodiments, the engineered antibody derivatives have reducedsize of the antigen-binding Ig-derived recombinant proteins(“miniaturized” full-size mAbs), produced by removing domains deemednon-essential for function. One of the best examples is SMIPs.

A Small modular immunopharmaceutical, or SMIP, is an artificial proteinlargely built from parts of antibodies (immunoglobulins), and isintended for use as a pharmaceutical drug. SMIPs have similar biologicalhalf-life as antibodies, but are smaller than antibodies and hence mayhave better tissue penetration properties. SMIPs are single-chainproteins that comprise one binding region, one hinge region as aconnector, and one effector domain. The binding region comprises amodified single-chain variable fragment (scFv), and the rest of theprotein can be constructed from the Fc (such as CH2, and CH3 as theeffector domain) and the hinge region of an antibody, such as IgG1.Genetically modified cells produce SMIPs as antibody-like dimers thatare about 30% smaller than real antibodies.

Another example of such engineered miniaturized antibody is “unibody,”in which the hinge region has been removed from IgG4 molecules. IgG4molecules are unstable and can exchange light-heavy chain heterodimerswith one another. Deletion of the hinge region prevents heavychain-heavy chain pairing entirely, leaving highly specific monovalentlight/heavy heterodimers, while retaining the Fc region to ensurestability and half-life in vivo.

A single-domain antibody (sdAb, including but not limited to thosecalled nanobody by Ablynx) is an antibody fragment consisting of asingle monomeric variable antibody domain. Like a whole antibody, it isable to bind selectively to a specific antigen, but is much smaller dueto its molecular weight of only 12-15 kDa. In certain embodiments, thesingle-domain antibody is engineered from heavy-chain antibodies(hcIgG). The first such sdAb was engineered based on an hcIgG found incamelids, called V_(H)H fragments. In certain embodiments, thesingle-domain antibody is engineered from IgNAR (“immunoglobulin newantigen receptor,” see below) using a V_(NAR) fragment. Cartilaginousfishes (such as shark) have such heavy-chain IgNAR antibodies. Incertain embodiments, the sdAb is engineered by splitting the dimericvariable domains from common immunoglobulin G (IgG), such as those fromhumans or mice, into monomers. In certain embodiments, a nanobody isderived from a heavy chain variable domain. In certain embodiments, ananobody is derived from light chain variable domain. In certainembodiments, the sdAb is obtained by screening libraries of singledomain heavy chain sequences (e.g., human single domain HCs) for bindersto a target antigen.

The single variable new antigen receptor domain antibody fragments(V_(NAR)s, or V_(NAR) domains) are derived from cartilaginous fish(e.g., shark) immunoglobulin new antigen receptor antibodies (IgNARs).Being one of the smallest known immunoglobulin-based protein scaffolds,such single domain proteins demonstrate favorable size and crypticepitope recognition properties. Mature IgNAR antibodies consist ofhomodimers of one variable new antigen receptor (V_(NAR)) domain andfive constant new antigen receptor (C_(NAR)) domains. This molecule ishighly stable, and possesses efficient binding characteristics. Itsinherent stability can likely be attributed to both (i) the underlyingIg scaffold, which presents a considerable number of charged andhydrophilic surface exposed residues compared to the conventionalantibody VH and VL domains found in murine antibodies; and (ii)stabilizing structural features in the complementary determining region(CDR) loops including inter-loop disulphide bridges, and patterns ofintra-loop hydrogen bonds.

A minibody is an engineered antibody fragment comprising an scFv linkedto a CH domain, such as the CH3γ1 (CH3 domain of IgG1) or CH4ε (CH4domain of IgE). For example, an scFv specific for carcinoembryonicantigen (CEA) has been linked to the CH3γ1 to create a minibody, whichhas previously been demonstrated to possess excellent tumor targetingcoupled with rapid clearance in vivo (Hu et al., Cancer Res.56:3055-3061, 1996). The scFv may have a N-terminal VH or VL. Thelinkage may be a short peptide (e.g., two amino acid linker, such asValGlu) that resultes in a non-covalent, hingeless minibody.Alternatively, the linkage may be an IgG1 hinge and a GlySer linkerpeptide that produces a covalent, hinge-minibody.

Natural antibodies are mono-specific, but bivalent, in that they expresstwo identical antigen-binding domains. In contrast, in certainembodiments, certain engineered antibody derivatives are bi- ormulti-specific molecules possess two or more different antigen-bindingdomains, each with different target specificity. Bispecific antibodiescan be generated by fusing two antibody-producing cells, each withdistinct specificity. These “quadromas” produced multiple molecularspecies, as the two distinct light chains and two distinct heavy chainswere free to recombine in the quadromas in multiple configurations.Since then, bispecific Fabs, scFvs and full-size mAbs have beengenerated using a variety of technologies (see above).

The dual variable domain immunoglobulin (DVD-Ig) protein is a type ofdual-specific IgG that simultaneously target two antigens/epitopes(DiGiammarino et al., Methods Mol Biol. 899:145-56, 2012). The moleculecontains an Fc region and constant regions in a configuration similar toa conventional IgG. However, the DVD-Ig protein is unique in that eacharm of the molecule contains two variable domains (VDs). The VDs withinan arm are linked in tandem and can possess different bindingspecificities.

Trispecific antibody derivative molecules can also been generated by,for example, expressing bispecific antibodies with two distinct Fabs andan Fc. One example is a mouse IgG2a anti-Ep-CAM, rat IgG2b anti-CD3quadroma, called BiUII, which is thought to permit the co-localizationof tumor cells expressing Ep-CAM, T cells expressing CD3, andmacrophages expressing FCγRI, thus potentiating the costimulatory andanti-tumor functions of the immune cells.

Probodies are fully recombinant, masked monoclonal antibodies thatremain inert in healthy tissue, but are activated specifically in thedisease microenvironment (e.g., through protease cleavage by a proteaseenriched or specific in a disease microenvironment). See Desnoyers etal., Sci Transl Med 5:207ra144, 2013. Similar masking techniques can beused for any of the antibodies or antigen-binding portions thereofdescribed herein.

An intrabody is an antibody that has been modified for intracellularlocalization, for working within the cell to bind to an intracellularantigen. The intrabody may remain in the cytoplasm, or may have anuclear localization signal, or may have a KDEL sequence for ERtargeting. The intrabody may be a single-chain antibody (scFv), modifiedimmunoglobulin VL domains with hyperstability, selected antibodyresistant to the more reducing intracellular environment, or expressedas a fusion protein with maltose binding protein or other stableintracellular proteins. Such optimizations have improved the stabilityand structure of intrabodies, and may have general applicability to anyof the antibodies or antigen-binding portions thereof described herein.

The antigen-binding portions or derivative antibodies of the inventionmay have substantially the same or identical (1) light chain and/orheavy chain CDR3 regions; (2) light chain and/or heavy chain CDR1, CDR2,and CDR3 regions; or (3) light chain and/or heavy chain regions,compared to an antibody from which they are derived/engineered.Sequences within these regions may contain conservative amino acidsubstitutions, including substitutions within the CDR regions. Incertain embodiments, there is no more than 1, 2, 3, 4, or 5 conservativesubstitutions. In an alternative, the antigen-binding portions orderivative antibodies have a light chain region and/or a heavy chainregion that is at least about 90%, 95%, 99% or 100% identical to anantibody from which they are derived/engineered. These antigen-bindingportions or derivative antibodies may have substantially the samebinding specificity and/or affinity to the target antigen compared tothe antibody. In certain embodiments, the K_(d) and/or k_(off) values ofthe antigen-binding portions or derivative antibodies are within 10-fold(either higher or lower), 5-fold (either higher or lower), 3-fold(either higher or lower), or 2-fold (either higher or lower) of anantibody described herein.

In certain embodiments, the antigen-binding portions or derivativeantibodies may be derived/engineered from fully human antibodies,humanized antibodies, or chimeric antibodies, and may be producedaccording to any art-recognized methods.

Monoclonal antibody techniques allow for the production of extremelyspecific cell-binding agents in the form of specific monoclonalantibodies. Particularly well known in the art are techniques forcreating monoclonal antibodies produced by immunizing mice, rats,hamsters or any other mammal with the antigen of interest such as theintact target cell, antigens isolated from the target cell, whole virus,attenuated whole virus, and viral proteins such as viral coat proteins.Sensitized human cells can also be used. Another method of creatingmonoclonal antibodies is the use of phage libraries of scFv (singlechain variable region), specifically human scFv (see e.g., Griffiths etal., U.S. Pat. Nos. 5,885,793 and 5,969,108; McCafferty et al., WO92/01047; Liming et al., WO 99/06587). In addition, resurfacedantibodies disclosed in U.S. Pat. No. 5,639,641 may also be used, as maychimeric antibodies and humanized antibodies.

Cell-binding agent can also be peptides derived from phage display (see,for example, Wang et al., Proc. Natl. Acad. Sci. USA (2011) 108(17),6909-6914) or peptide library techniques (see, for example, Dane et al.,Mol. Cancer. Ther. (2009) 8(5):1312-1318).

In certain embodiments, the CBA of the invention also includes anantibody mimetic, such as a DARPin, an affibody, an affilin, an affitin,an anticalin, an avimer, a Fynomer, a Kunitz domain peptide, a monobody,or a nanofitin.

As used herein, the terms “DARPin” and “(designed) ankyrin repeatprotein” are used interchangeably to refer to certain geneticallyengineered antibody mimetic proteins typically exhibiting preferential(sometimes specific) target binding. The target may be protein,carbohydrate, or other chemical entities, and the binding affinity canbe quite high. The DARPins may be derived from natural ankyrinrepeat-containing proteins, and preferably consist of at least three,usually four or five ankyrin repeat motifs (typically about 33 residuesin each ankyrin repeat motif) of these proteins. In certain embodiments,a DARPin contains about four- or five-repeats, and may have a molecularmass of about 14 or 18 kDa, respectively. Libraries of DARPins withrandomized potential target interaction residues with diversities ofover 10¹² variants can be generated at the DNA level, for use inselecting DARPins that bind desired targets (e.g., acting as receptoragonists or antagonists, inverse agonists, enzyme inhibitors, or simpletarget protein binders) with picomolar affinity and specificity, using avariety of technologies such as ribosome display or signal recognitionparticle (SRP) phage display. See, for example, U.S. Patent PublicationNos. 2004/0132028, 2009/0082274, 2011/0118146, and 2011/0224100, WO02/20565 and WO 06/083275 for DARPin preparation (the entire teachingsof which are incorporated herein by reference), and also see C. Zahnd etal. (2010) Cancer Res., 70:1595-1605; Zahnd et al. (2006) J. Biol.Chem., 281(46):35167-35175; and Binz, H. K., Amstutz, P. & Pluckthun, A.(2005) Nature Biotechnology, 23:1257-1268 (all incorporated herein byreference). Also see U.S. Patent Publication No. 2007/0238667; U.S. Pat.No. 7,101,675; WO 2007/147213; and WO 2007/062466 (the entire teachingsof which are incorporated herein by reference), for the relatedankyrin-like repeats protein or synthetic peptide.

Affibody molecules are small proteins engineered to bind to a largenumber of target proteins or peptides with high affinity, thus imitatingmonoclonal antibodies. An Affibody consists of three alpha helices with58 amino acids and has a molar mass of about 6 kDa. They have been shownto withstand high temperatures (90° C.) or acidic and alkalineconditions (pH 2.5 or pH 11), and binders with an affinity of down tosub-nanomolar range have been obtained from naïve library selections,and binders with picomolar affinity have been obtained followingaffinity maturation. In certain embodiments, affibodies are conjugatedto weak electrophiles for binding to targets covalently.

Monobodies (also known as Adnectins), are genetically engineeredantibody mimetic proteins capable of binding to antigens. In certainembodiments, monobodies consist of 94 amino acids and have a molecularmass of about 10 kDa. They are based on the structure of humanfibronectin, more specifically on its tenth extracellular type IIIdomain, which has a structure similar to antibody variable domains, withseven beta sheets forming a barrel and three exposed loops on each sidecorresponding to the three complementarity determining regions.Monobodies with specificity for different proteins can be tailored bymodifying the loops BC (between the second and third beta sheets) and FG(between the sixth and seventh sheets).

A tribody is a self-assembly antibody mimetic designed based on theC-terminal coiled-coil region of mouse and human cartilage matrixprotein (CMP), which self-assembles into a parallel trimeric complex. Itis a highly stable trimeric targeting ligand created by fusing aspecific target-binding moiety with the trimerization domain derivedfrom CMP. The resulting fusion proteins can efficiently self-assembleinto a well-defined parallel homotrimer with high stability. Surfaceplasmon resonance (SPR) analysis of the trimeric targeting ligandsdemonstrated significantly enhanced target-binding strength comparedwith the corresponding monomers. Cellular-binding studies confirmed thatsuch tribodies have superior binding strength toward their respectivereceptors.

A Centyrin is another antibody mimetic that can be obtained using alibrary built upon the framework of a consensus FN3 domain sequence(Diem et al., Protein Eng Des Sel., 2014). This library employsdiversified positions within the C-strand, CD-loop, F-strand and FG-loopof the FN3 domain, and high-affinity Centyrin variants can be selectedagainst specific targets.

In one embodiment, the cell-binding agent is an anti-folate receptorantibody. More specifically, the anti-folate receptor antibody is ahumanized antibody or antigen binding fragment thereof that specificallybinds a human folate receptor 1 (also known as folate receptor alpha(FR-α)). The terms “human folate receptor 1,” “FOLR1,” or “folatereceptor alpha (FR-α)”, as used herein, refers to any native humanFOLR1, unless otherwise indicated. Thus, all of these terms can refer toeither a protein or nucleic acid sequence as indicated herein. The term“FOLR1” encompasses “full-length,” unprocessed FOLR1 as well as any formof FOLR1 that results from processing within the cell. The FOLR1antibody comprises: (a) a heavy chain CDR1 comprising GYFMN (SEQ ID NO:1); a heavy chain CDR2 comprising RIHPYDGDTFYNQXaa₁FXaa₂Xaa₃ (SEQ ID NO:2); and a heavy chain CDR3 comprising YDGSRAMDY (SEQ ID NO: 3); and (b)a light chain CDR1 comprising KASQSVSFAGTSLMH (SEQ ID NO: 4); a lightchain CDR2 comprising RASNLEA (SEQ ID NO: 5); and a light chain CDR3comprising QQSREYPYT (SEQ ID NO: 6); wherein Xaa₁ is selected from K, Q,H, and R; Xaa₂ is selected from Q, H, N, and R; and Xaa₃ is selectedfrom G, E, T, S, A, and V. Preferably, the heavy chain CDR2 sequencecomprises RIHPYDGDTFYNQKFQG (SEQ ID NO: 7).

In another embodiment, the anti-folate receptor antibody is a humanizedantibody or antigen binding fragment thereof that specifically binds thehuman folate receptor 1 comprising the heavy chain having the amino acidsequence of

(SEQ ID NO: 8) QVQLVQSGAEVVKPGASVKISCKASGYTFTGYFMNWVKQSPGQSLEWIGRIHPYDGDTFYNQKFQGKATLTVDKSSNTAHMELLSLTSEDFAVYYCTRYDGSRAMDYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK.

In another embodiment, the anti-folate antibody receptor is a humanizedantibody or antigen binding fragment thereof encoded by the plasmid DNAdeposited with the ATCC on Apr. 7, 2010 and having ATCC deposit nos.PTA-10772 and PTA-10773 or 10774.

In another embodiment, the anti-folate receptor antibody is a humanizedantibody or antigen binding fragment thereof that specifically binds thehuman folate receptor 1 comprising the light chain having the amino acidsequence of

(SEQ ID NO: 9) DIVLTQSPLSLAVSLGQPAIISCKASQSVSFAGTSLMHWYHQKPGQQPRLLIYRASNLEAGVPDRFSGSGSKTDFTLNISPVEAEDAATYYCQQSREYPYTFGGGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEV THQGLSSPVTKSFNRGEC;or (SEQ ID NO: 10) DIVLTQSPLSLAVSLGQPAIISCKASQSVSFAGTSLMHWYHQKPGQQPRLLIYRASNLEAGVPDRFSGSGSKTDFTLTISPVEAEDAATYYCQQSREYPYTFGGGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEV THQGLSSPVTKSFNRGEC.

In another embodiment the anti-folate receptor antibody is a humanizedantibody or antigen binding fragment thereof that specifically binds thehuman folate receptor 1 comprising the heavy chain having the amino acidsequence of SEQ ID NO: 8, and the light chain having the amino acidsequence of SEQ ID NO: 9 or SEQ ID NO: 10. Preferably, the antibodycomprises the heavy chain having the amino acid sequence of SEQ ID NO: 8and the light chain having the amino acid sequence of SEQ ID NO: 10 (huFOLR1).

In another embodiment, the anti-folate receptor antibody is a humanizedantibody or antigen binding fragment thereof encoded by the plasmid DNAdeposited with the ATCC on Apr. 7, 2010 and having ATCC deposit nos.PTA-10772 and PTA-10773 or 10774.

In another embodiment, the anti-folate receptor antibody is a humanizedantibody or antigen binding fragment thereof that specifically binds thehuman folate receptor 1, and comprising a heavy chain variable domain atleast about 90%, 95%, 99% or 100% identical toQVQLVQSGAEVVKPGASVKISCKASGYTFTGYFMNWVKQSPGQSLEWIGRIHPYDGDTFYNQKFQGKATLTVDKSSNTAHMELLSLTSEDFAVYYCTRYDGSRAM DYWGQGTTVTVSS (SEQID NO: 11), and a light chain variable domain at least about 90%, 95%,99% or 100% identical to

(SEQ ID NO: 12) DIVLTQSPLSLAVSLGQPAIISCKASQSVSFAGTSLMHWYHQKPGQQPRLLIYRASNLEAGVPDRFSGSGSKTDFTLNISPVEAEDAATYYCQQSREYPY TFGGGTKLEIKR; or(SEQ ID NO: 13) DIVLTQSPLSLAVSLGQPAIISCKASQSVSFAGTSLMHWYHQKPGQQPRLLIYRASNLEAGVPDRFSGSGSKTDFTLTISPVEAEDAATYYCQQSREYPY TFGGGTKLEIKR.

In another embodiment, the anti-folated receptor antibody is huMov19 orM9346A (see, for example, U.S. Pat. No. 8,709,432, U.S. Pat. No.8,557,966, and WO2011106528, all incorporated herein by reference).

In another embodiment, the cell-binding agent is an anti-EGFR antibodyor an antibody fragment thereof. In one embodiment, the anti-EGFRantibody is a non-antagonist antibody, including, for example, theantibodies described in WO2012058592, herein incorporated by reference.In another embodiment, the anti-EGFR antibody is a non-functionalantibody, for example, humanized ML66 or EGFR-8. More specifically, theanti-EGFR antibody is huML66.

In yet another embodiment, the anti-EGFR antibody comprising the heavychain having the amino acid sequence of SEQ ID NO: 14, and the lightchain having the amino acid sequence of SEQ ID NO: 15. As used herein,double underlined sequences represent the variable regions (i.e., heavychain variable region or HCVR, and light chain variable region or LCVR)of the heavy or light chain sequences, while bold sequences representthe CDR regions (i.e., from N-terminal to C-terminal, CDR1, CDR2, andCDR3, respectively, of the heavy chain or light chain sequences).

Full-Length Heavy/Light Chain Amino Antibody Acid Sequence huML66HCQVQLQESGPGLVKPSETLSLTCTVSGLSLASNSVSWIR QPPGKGLEWMGVIWNHGGTDYNPSIKSRLSISRDTSKS QVFLKMNSLTAADTAMYFCVRKGGIYFDYWGQGV LVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLEPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQ GNVFSCSVMHEALHNHYTQKSLSLSPG(SEQ ID NO: 14) huML66LC DTVLTQSPSLAVSPGERATISCRASESVSTLMHWYQQKPGQQPKLLIYLASHRESGVPARFSGSGSGTDFTLTIDPMEAEDTATYYCQQSRNDPWTFGQGTKLELKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKV YACEVTHQGLSSPVTKSFNRGEC(SEQ ID NO: 15)

In yet another embodiment, the anti-EGFR antibody comprises the heavychain CDR1-CDR3 of SEQ ID NO: 14, and/or the light chain CDR1-CDR3 ofSEQ ID NO: 15, and preferrably specifically binds EGFR.

In yet another embodiment, the anti-EGFR antibody comprises a heavychain variable region (HCVR) sequence at least about 90%, 95%, 97%, 99%,or 100% identical to SEQ ID NO: 14, and/or a light chain variable region(LCVR) sequence at least about 90%, 95%, 97%, 99%, or 100% identical toSEQ ID NO: 15, and preferrably specifically binds EGFR.

In another embodiment, the anti-EGFR antibody are antibodies describedin U.S. Pat. No. 8,790,649 and WO 2012/058588, herein incorporated byreference. In one embodiment, the anti-EGFR antibody is huEGFR-7Rantibody.

In one embodiment, the anti-EGFR antibody comprises an immunoglobulinheavy chain region having the amino acid sequence ofQVQLVQSGAEVAKPGASVKLSCKASGYTFTSYWMQWVKQRPGQGLECIGTIYPGDGDTTYTQKFQGKATLTADKSSSTAYMQLSSLRSEDSAVYYCARYDAPGYAMDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO:16) and an immunoglobulin light chainregion having the amino acid sequence ofDIQMTQSPSSLSASVGDRVTITCRASQDINNYLAWYQHKPGKGPKLLIHYTSTLHPGIPSRFSGSGSGRDYSFSISSLEPEDIATYYCLQYDNLLYTFGQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO:17), or animmunoglobulin light chain region having the amino acid sequence ofDIQMTQSPSSLSASVGDRVTITCKASQQDINNYLAWYQHKPGKGPKLLIHYTSTLHPGIPSRFSGSGSGRDYSFSISSLEPEDIATYYCLQYDNLLYTFGQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO:18).

In another embodiment, the anti-EGFR antibody comprises animmunoglobulin heavy chain region having the amino acid sequence setforth in SEQ ID NO:16 and an immunoglobulin light chain region havingthe amino acid sequence set forth in SEQ ID NO:17.

In another embodiment, the anti-EGFR antibody comprises animmunoglobulin heavy chain region having the amino acid sequence setforth in SEQ ID NO:16 and an immunoglobulin light chain region havingthe amino acid sequence set forth in SEQ ID NO:18.

In yet another embodiment, the anti-EGFR antibody comprises the heavychain CDR1-CDR3 of SEQ ID NO: 16, and/or the light chain CDR1-CDR3 ofSEQ ID NO: 17 or 18, and preferrably specifically binds EGFR.

In yet another embodiment, the anti-EGFR antibody comprises a heavychain variable region (HCVR) sequence at least about 90%, 95%, 97%, 99%,or 100% identical to SEQ ID NO: 16, and/or a light chain variable region(LCVR) sequence at least about 90%, 95%, 97%, 99%, or 100% identical toSEQ ID NO: 17 or 18, and preferrably specifically binds EGFR.

In another embodiment, the cell-binding agent is an anti-CD19 antibody,such as those described in U.S. Pat. No. 8,435,528 and WO2004/103272,herein incorporated by reference. In one embodiment, the anti-CD19antibody comprises an immunoglobulin heavy chain region having the aminoacid sequence of QVQLVQPGAEVVKPGASVKLSCKTSGYTFTSNWMHWVKQAPGQGLEWIGEIDPSDSYTNYNQNFQGKAKLTVDKSTSTAYMEVSSLRSDDTAVYYCARGSNPYYYAMDYWGQGTSVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 19) and an immunoglobulin light chainregion having the amino acid sequence of

(SEQ ID NO: 20) EIVLTQSPAIMSASPGERVTMTCSASSGVNYMHWYQQKPGTSPRRWIYDTSKLASGVPARFSGSGSGTDYSLTISSMEPEDAATYYCHQRGSYTFGGGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSS PVTKSFNRGEC.

In another embodiment, the anti-CD19 antibody is huB4 antibody.

In yet another embodiment, the anti-CD19 antibody comprises the heavychain CDR1-CDR3 of SEQ ID NO: 19, and/or the light chain CDR1-CDR3 ofSEQ ID NO: 20, and preferrably specifically binds CD19.

In yet another embodiment, the anti-CD19 antibody comprises a heavychain variable region (HCVR) sequence at least about 90%, 95%, 97%, 99%,or 100% identical to SEQ ID NO: 19, and/or a light chain variable region(LCVR) sequence at least about 90%, 95%, 97%, 99%, or 100% identical toSEQ ID NO: 20, and preferrably specifically binds CD19.

In yet another embodiment, the cell-binding agent is an anti-Muc1antibody, such as those described in U.S. Pat. No. 7,834,155, WO2005/009369 and WO 2007/024222, herein incorporated by reference. In oneembodiment, the anti-Muc1 antibody comprises an immunoglobulin heavychain region having the amino acid sequence ofQAQLVQSGAEVVKPGASVKMSCKASGYTFTSYNMHWVKQTPGQGLEWIGYIYPGNGATNYNQKFQGKATLTADTSSSTAYMQISSLTSEDSAVYFCARGDSVPFAYWGQGTLVTVSAASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO:21) and an immunoglobulin light chainregion having the amino acid sequence of

(SEQ ID NO: 22) EIVLTQSPATMSASPGERVTITCSAHSSVSFMHWFQQKPGTSPKLWIYST SSLASGVPARFGGSGSGTSYSLTISSMEAEDAATYYCQQRSSFPLTFGAGTKLELKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGL SSPVTKSFNRGEC.

In another embodiment, the anti-Muc1 antibody is huDS6 antibody.

In yet another embodiment, the anti-Muc1 antibody comprises the heavychain CDR1-CDR3 of SEQ ID NO: 21, and/or the light chain CDR1-CDR3 ofSEQ ID NO: 22, and preferrably specifically binds Muc1.

In yet another embodiment, the anti-Muc1 antibody comprises a heavychain variable region (HCVR) sequence at least about 90%, 95%, 97%, 99%,or 100% identical to SEQ ID NO: 21, and/or a light chain variable region(LCVR) sequence at least about 90%, 95%, 97%, 99%, or 100% identical toSEQ ID NO: 22, and preferrably specifically binds Muc1.

In another embodiment, the cell-binding agent is an anti-CD33 antibodyor fragment thereof, such as the antibodies or fragments thereofdescribed in U.S. Pat. Nos. 7,557,189, 7,342,110, 8,119,787 and8,337,855 and WO2004/043344, herein incorporated by reference. Inanother embodiment, the anti-CD33 antibody is huMy9-6 antibody.

In one embodiment, the anti-CD33 antibody comprises an immunoglobulinheavy chain region having the amino acid sequence ofQVQLQQPGAEVVKPGASVKMSCKASGYTFTSYYIHWIKQTPGQGLEWVGVIYPGNDDISYNQKFQGKATLTADKSSTTAYMQLSSLTSEDSAVYYCAREVRLRYFDVWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO:23), and an immunoglobulin light chainregion having the amino acid sequence of

(SEQ ID NO: 24) EIVLTQSPGSLAVSPGERVTMSCKSSQSVFFSSSQKNYLAWYQQIPGQSPRLLIYWASTRESGVPDRFTGSGSGTDFTLTISSVQPEDLAIYYCHQYLSSRTFGQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACE VTHQGLSSPVTKSFNRGEC.

In yet another embodiment, the anti-CD33 antibody comprises the heavychain CDR1-CDR3 of SEQ ID NO: 23, and/or the light chain CDR1-CDR3 ofSEQ ID NO: 24, and preferrably specifically binds CD33.

In yet another embodiment, the anti-CD33 antibody comprises a heavychain variable region (HCVR) sequence at least about 90%, 95%, 97%, 99%,or 100% identical to SEQ ID NO: 23, and/or a light chain variable region(LCVR) sequence at least about 90%, 95%, 97%, 99%, or 100% identical toSEQ ID NO: 24, and preferrably specifically binds CD33.

In another embodiment, the cell-binding agent is an anti-CD37 antibodyor an antibody fragment thereof, such as those described in U.S. Pat.No. 8,765,917 and WO 2011/112978, herein incorporated by reference. Inone embodiment, the anti-CD37 antibody is huCD37-3 antibody.

In one embodiment, the anti-CD37 antibody comprises an immunoglobulinlight chain region having the amino acid sequence ofDIQMTQSPSSLSVSVGERVTITCRASENIRSNLAWYQQKPGKSPKLLVNVATNLADGVPSRFSGSGSGTDYSLKINSLQPEDFGTYYCQHYWGTTWTFGQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO:25) andan immunoglobulin heavy chain region having the amino acid sequence ofQVQVQESGPGLVAPSQTLSITCTVSGFSLTTSGVSWVRQPPGKGLEWLGVIWGDGSTNYHPSLKSRLSIKKDHSKSQVFLKLNSLTAADTATYYCAKGGYSLAHWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEAL HNHYTQKSLSLSPG(SEQ ID NO:26), or an immunoglobulin heavy chain region having the aminoacid sequence of

(SEQ ID NO: 27) QVQVQESGPGLVAPSQTLSITCTVSGFSLTTSGVSWVRQPPGKGLEWLGV IWGDGSTNYHSSLKSRLSIKKDHSKSQVFLKLNSLTAADTATYYCAKGGY SLAHWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG

In another embodiment, the anti-CD37 antibody comprises animmunoglobulin light chain region having the amino acid sequence setforth in SEQ ID NO:25 and an immunoglobulin heavy chain region havingthe amino acid sequence set forth in SEQ ID NO:26.

In yet another embodiment, the anti-CD37 antibody comprises animmunoglobulin light chain region having the amino acid sequence setforth in SEQ ID NO:25 and an immunoglobulin heavy chain region havingthe amino acid sequence set forth in SEQ ID NO:27.

In yet another embodiment, the anti-CD37 antibody comprises the heavychain CDR1-CDR3 of SEQ ID NO: 26 or 27, and/or the light chain CDR1-CDR3of SEQ ID NO: 25, and preferrably specifically binds CD37.

In yet another embodiment, the anti-CD37 antibody comprises a heavychain variable region (HCVR) sequence at least about 90%, 95%, 97%, 99%,or 100% identical to SEQ ID NO: 26 or 27, and/or a light chain variableregion (LCVR) sequence at least about 90%, 95%, 97%, 99%, or 100%identical to SEQ ID NO: 25, and preferrably specifically binds CD37.

In yet another embodiment, the anti-CD37 antibody comprises animmunoglobulin light chain region having the amino acid sequence ofEIVLTQSPATMSASPGERVTMTCSATSSVTYMHWYQQQQKPGQSPKRWIYDTSNLPYGVPARFSGSGSGTSYSLTISSMEAEDAATYYCQQWSDNPPTFGQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO:28) andan immunoglobulin heavy chain reion having the amino acid sequence of

(SEQ ID NO: 29) QVQLQESGPGLLKPSQSLSLTCTVSGYSITSGFAWHWIRQHPGNKLEWMGYILYSGSTVYSPSLKSRISITRDTSKNHFFLQLNSVTAADTATYYCARGYYGYGAWFAYWGQGTLVTVSAASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG.

In yet another embodiment, the anti-CD37 antibody comprises the heavychain CDR1-CDR3 of SEQ ID NO: 29, and/or the light chain CDR1-CDR3 ofSEQ ID NO: 28, and preferrably specifically binds CD37.

In yet another embodiment, the anti-CD37 antibody comprises a heavychain variable region (HCVR) sequence at least about 90%, 95%, 97%, 99%,or 100% identical to SEQ ID NO: 29, and/or a light chain variable region(LCVR) sequence at least about 90%, 95%, 97%, 99%, or 100% identical toSEQ ID NO: 28, and preferrably specifically binds CD37.

In yet another embodiment, the anti-CD37 antibody is huCD37-50 antibody.

Cell-Binding Agent-Drug Conjugates

The present invention also provides cell-binding agent-drug conjugatescomprising a cell-binding agent linked to one or more cytotoxiccompounds of the present invention via a variety of linkers, including,but not limited to, disulfide linkers, thioether linkers, amide bondedlinkers, peptidase-labile linkers, acid-labile linkers, esterase-labilelinkers.

In a second embodiment, the invention provides a conjugate comprising: acytotoxic compound and a cell binding agent (CBA), wherein the cytotoxiccompound is covalently covalently linked to the CBA, and wherein thecytotoxic compound is represented by structural formulas (I′), (II′),(III′), (IV′), (V′) or (VI′), wherein the variables are as describedabove.

In certain embodiments, the cytotoxic compound is represented bystructural formula (I′) or a pharmaceutically acceptable salt thereof.

In certain embodiments, for structural formulas (I′), (II′), (III′),(IV′), (V′) and (VI′), one of L′, L″ and L′″ is represented by formula(A′):

—Z₁—P—Z₂—R_(x)-J′  (A′),

and the others are —H, an linear or branched alkyl having from 1 to 6carbon atoms, halogen, —OH, (C₁-C₆)alkoxy, or —NO₂. Specifically, one ofL′, L″ and L′″ is represented by formula (A′), and the others are —H.

In a 1^(st) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), L′ is represented by formula (A′) and L″and L′″ are both —H; and the remaining variables are as described abovein the first embodiment.

In a 2^(nd) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), R_(x) is a linear, branched or cyclicalkyl having 1 to 6 carbon atoms optionally substituted with halogen,—OH, (C₁-C₃)alkyl, (C₁-C₃)alkoxy, halo(C₁-C₃)alkyl, or a chargedsubstituent or an ionizable group Q; and the remaining variables are asdescribed above in the first embodiment or the 1^(st) specificembodiment.

In certain embodiments, Q is i) —SO₃H, —Z′—SO₃H, —OPO₃H₂, —Z′—OPO₃H₂,—PO₃H₂, —Z′—PO₃H₂, —CO₂H, —Z′—CO₂H, —NR₁₁R₁₂, or —Z′—NR₁₁R₁₂, or apharmaceutically acceptable salt thereof; or, ii) —N⁺R₁₄R₁₅R₁₆X⁻ or—Z′—N⁺R₁₄R₁₅R₁₆X⁻; Z′ is an optionally substituted alkylene, anoptionally substituted cycloalkylene or an optionally substitutedphenylene; R₁₄ to R₁₆ are each independently an optionally substitutedalkyl; and X⁻ is a pharmaceutically acceptable anion; and the remainingvariables are as described above in the 2^(nd) specific embodiment. Morespecifically, Q is —SO₃H or a pharmaceutically acceptable salt thereof.

In a 3^(rd) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), J′ comprises a moiety that is covalentlylinked to the CBA, and is —NR^(c1) or —C(═O)—, wherein R^(c1) is —H orlinear or branched alkyl having 1 to 4 carbon atoms optionallysubstituted with halogen, —OH or (C₁-C₃)alkoxy; and the remainingvariables are as described above in the first embodiment or the 1^(st)or 2^(nd) specific embodiment.

In certain embodiments, J′ is —C(═O)—; and the remaining variables areas described above in the 3^(rd) specific embodiment.

In a 4^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), L′ is represented by the followingformula:

—NR₅—P—C(═O)—(CR_(a)R_(b))_(m)-J′  (B1′);

—NR₅—P—C(═O)—Cy-(CR_(a)R_(b))_(m′)-J′  (B2′);

—C(═O)—P—NR₅—(CR_(a)R_(b))_(m)-J′  (C1′); or

—C(═O)—P—NR₅—Cy-(CR_(a)R_(b))_(m′)-J′  (C2′),

wherein:

-   -   J′ is —C(═O)—;    -   R_(a) and R_(b), for each occurrence, are each independently —H,        (C₁-C₃)alkyl or a charged substituent or an ionizable group Q;    -   m is an integer from 1 to 6;    -   m′ is 0 or an integer from 1 to 6; and    -   Cy is a cyclic alkyl having 5 or 6 ring carbon atoms optionally        substituted with halogen, —OH, (C₁-C₃)alkyl, (C₁-C₃)alkoxy, or        halo(C₁-C₃)alkyl; and the remaining variables are as described        above in the first embodiment or the 1^(st), 2^(nd) or 3^(rd)        specific embodiment.

In certain embodiments, R_(a) and R_(b) are both H; Cy for formulas(B2′) and (C2′) is cyclohexane; and R₅ is H or Me; and the remainingvariables are as described above in the 4^(th) specific embodiment. Morespecifically, m′ in formulas (B2′) and (C2′) is 0 or 1.

In a 5^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), L′ is represented by the followingformula:

—NR₅—P—C(═O)—(CR_(a)R_(b))_(m)—S—Z^(s1)  (B3′); or

—C(═O)—P—NR₅—(CR_(a)R_(b))_(m)—S—Z^(s1)  (C3′),

wherein:

-   -   R_(a) and R_(b), for each occurrence, are each independently —H,        (C₁-C₃)alkyl, or a charged substituent or an ionizable group Q;    -   m is an integer from 1 to 6;    -   Z^(s1) is selected from any one of the following formulas:

wherein:

-   -   q is an integer fro 1 to 5;    -   n′ is an integer from 2 to 6;    -   U is —H or SO₃M;    -   M is a pharmaceutically acceptable cation (e.g., H⁺, Na⁺ or K⁺);        and the remaining variables are as described above in the first        embodiment or the 1^(st), 2^(nd), 3^(rd) or 4^(th) specific        embodiment.

In certain embodiments, the charged substituent or an ionizable group Qis i) —SO₃H, —Z′—SO₃H, —OPO₃H₂, —Z′—OPO₃H₂, —PO₃H₂, —Z′—PO₃H₂, —CO₂H,—Z′—CO₂H, —NR₁₁R₁₂, or —Z′—NR₁₁R₁₂, or a pharmaceutically acceptablesalt thereof; or, ii) —N⁺R₁₄R₁₅R₁₆X⁻ or —Z′—N⁺R₁₄R₁₅R₁₆X⁻; Z′ is anoptionally substituted alkylene, an optionally substituted cycloalkyleneor an optionally substituted phenylene; R₁₄ to R₁₆ are eachindependently an optionally substituted alkyl; and X⁻ is apharmaceutically acceptable anion; and the remaining variables are asdescribed above in the 5^(th) specific embodiment. More specifically, Qis —SO₃H or a pharmaceutically acceptable salt thereof.

In certain embodiments, R_(a) and R_(b) are both —H and R₅ is H or Me;and the remaining variables are as described above in the 5^(th)specific embodiment.

In certain embodiments, —(CR_(a)R_(b))_(m)— is —(CH₂)_(m″)—C(Me₂)- andm″ is an integer from 1 to 5; the remaining variables are as describedabove in the 5^(th) specific embodiment.

In a 6^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), P is a peptide containing 2 to 10 aminoacid residues; and the remaining variables are as described above in thefirst embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th) or 5^(th)specific embodiment.

In certain embodiments, P is a peptide containing 2 to 5 amino acidresidues; and the remaining variables are as described above in the6^(th) specific embodiment.

In certain embodiments, P is selected from Gly-Gly-Gly, Ala-Val,Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit, Leu-Cit,Lle-Cit, Trp, Cit, Phe-Ala, Phe-N⁹-tosyl-Arg, Phe-N⁹-nitro-Arg,Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu,Val-Ala-Val, Ala-Leu-Ala-Leu, β-Ala-Leu-Ala-Leu and Gly-Phe-Leu-Gly,Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit,D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg,D-Arg-D-Arg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met,Met-Ala; and the remaining variables are as described above in the6^(th) specific embodiment.

In certain embodiments, P is Gly-Gly-Gly, Ala-Val, Ala-Ala, Ala-D-Ala,D-Ala-Ala, and D-Ala-D-Ala; and the remaining variables are as describedabove in the 6^(th) specific embodiment.

In a 7^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI), the double line

between N and C represents a double bond; and the remaining variablesare as described above in the first embodiment, or the 1^(st), 2^(nd),3^(rd), 4^(th), 5^(th) or 6^(th) specific embodiment.

In a 8^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), the double line

between N and C represents a single bond, X is —H or an amine protectinggroup; and Y is selected from —H, —OR, —OCOR′, —SR, —NR′R″, anoptionally substituted 5- or 6-membered nitrogen-containing heterocycle,—SO₃H, —SO₂H and —OSO₃H; ane the remaining variables are as described inthe first embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th),6^(th) or 7^(th) specific embodiment.

In certain embodiments, Y is selected from —H, —SO₃M, —OH, —OMe, —OEt or—NHOH, wherein M is —H, Na⁺ or K⁺; and the remaining variables are asdescribed above in the 8^(th) specific embodiment. More specifically, Yis —H, —SO₃M or —OH.

In a 9^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), X′ is selected from the group consistingof —H, —OH, an optionally substituted linear, branched or cyclic alkyl,alkenyl or alkynyl having from 1 to 10 carbon atoms, and phenyl; and theremaining variables are as described in the first embodiment or the1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th), 7^(th) or 8^(th)specific embodiment.

In certain embodiments, X′ is —H, —OH, (C₁-C₃)alkyl, halo(C₁-C₃)alkyl,or phenyl; and the remaining variables are as described above in the9^(th) specific embodiment. More specifically, X′ is —H, —OH or -Me.Even more specifically, X′ is —H.

In a 10^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), Y′ is —H, an oxo group, (C₁-C₃)alkyl orhalo(C₁-C₃)alkyl; and the remaining variables are as described in thefirst embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th),7^(th), 8^(th) or 9^(th) specific embodiment. More specifically, Y′ is—H or oxo. Even more specifically, Y′ is —H.

In a 11^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), A and A′ are the same or different, andare selected from —O—, —S—, —NR₅—, and oxo —(C═O)—; and the remainingvariables are as described in the first embodiment or the 1^(st),2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th), 7^(th), 8^(th), 9^(th) or10^(th) specific embodiment. More specifically, A and A′ are the same ordifferent, and are selected from —O— and —S—. Even more specifically, Aand A′ are —O—.

In a 12^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), R₆ is —OMe; and the remaining variablesare as described in the first embodiment or the 1^(st), 2^(nd), 3^(rd),4^(th), 5^(th), 6^(th), 7^(th), 8^(th), 9^(th), 10^(th) or 11^(th)specific embodiment.

In a 13^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ areindependently —H, halogen, —NO₂, —OH, (C₁-C₃)alkyl, halo(C₁-C₃)alkyl or(C₁-C₃)alkoxy; and the remaining variables are as described in the firstembodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th),7^(th), 8^(th), 9^(th), 10^(th), 11^(th) or 12^(th) specific embodiment.More specifically, R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ are all —H.

In a 14^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), R, R′, R″ and R₅ are each independently—H or (C₁-C₃)alkyl; and the remaining variables are as described in thefirst embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th), 6^(th),7^(th), 8^(th), 9^(th), 10^(th), 11^(th), 12^(th) or 13^(th) specificembodiment.

In a 14^(th) specific embodiment, for structural formulas (I′), (II′),(III′), (IV′), (V′) and (VI′), the double line

between N and C represents a single bond or double bond, provided thatwhen it is a double bond X is absent and Y is —H, and when it is asingle bond, X is —H, Y is —OH or —SO₃M;

-   -   R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ are all —H;    -   R₆ is —OMe;    -   X′ and Y′ are both —H;    -   A and A′ are —O—;    -   M is H, Na⁺ or K⁺; and the remaining variables are as described        in the first embodiment or the 1^(st), 2^(nd), 3^(rd), 4^(th),        5^(th) or 6^(th) specific embodiment.

In a 15^(th) specific embodiment, the conjugate of the present inventionis represented by any one of the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein:

-   -   r is an integer from 1 to 10;    -   Y is —H, —OH or —SO₃M; and    -   M is a pharmaceutically acceptable cation (e.g., H⁺, Na⁺ or K⁺).        More specifically, Y is —SO₃M. Alternatively, Y is —OH.

In certain embodiments, the conjugates described herein, such as thosedescribed in the second embodiment or the 1^(st) to 15^(th) specificembodiments, may comprise 1-10 cytotoxic compounds, 2-9 cytotoxiccompounds, 3-8 cytotoxic compounds, 4-7 cytotoxic compounds, or 5-6cytotoxic compounds, each cytotoxic compound comprising the linkinggroup linking the cytotoxic compound to the CBA, and each cytotoxiccompound on the conjugate is the same.

In any of the conjugates embodiments, such as the second embodiment orthe 1^(st) to 15^(th) specific embodiments, the cell-binding agent maybind to target cells selected from tumor cells, virus infected cells,microorganism infected cells, parasite infected cells, autoimmune cells,activated cells, myeloid cells, activated T-cells, B cells, ormelanocytes; cells expressing the CD4, CD6, CD19, CD20, CD22, CD30,CD33, CD37, CD38, CD40, CD44, CD56, EpCAM, CanAg, CALLA, or Her-2antigens; Her-3 antigens; or cells expressing insulin growth factorreceptor, epidermal growth factor receptor, and folate receptor.

In any of the conjugates embodiments, such as the second embodiment orthe 1^(st) to 15^(th) specific embodiments, the cell-binding agent maybe an antibody, a single chain antibody, an antibody fragment thatspecifically binds to the target cell, a monoclonal antibody, a singlechain monoclonal antibody, or a monoclonal antibody fragment thatspecifically binds to a target cell, a chimeric antibody, a chimericantibody fragment that specifically binds to the target cell, a domainantibody, a domain antibody fragment that specifically binds to thetarget cell, a lymphokine, a hormone, a vitamin, a growth factor, acolony stimulating factor, or a nutrient-transport molecule.

The antibody may be a resurfaced antibody, a resurfaced single chainantibody, or a resurfaced antibody fragment.

The antibody may be a monoclonal antibody, a single chain monoclonalantibody, or a monoclonal antibody fragment thereof.

The antibody may be a humanized antibody, a humanized single chainantibody, or a humanized antibody fragment.

In any of the conjugates embodiments above, such as the secondembodiment or the 1^(st) to 15^(th) specific embodiments, thecell-binding agent may be an anti-folate receptor antibody or anantibody fragment thereof. More specifically, the anti-folate receptorantibody is huMOV19 antibody.

Alternatively, in any of the conjugates embodiments above, such as thesecond embodiment or the 1^(st) to 15^(th) specific embodiments, thecell-binding agent may be an anti-EGFR antibody or an antibody fragmentthereof. In one embodiment, the anti-EGFR antibody is a non-antagonistantibody, including, for example, the antibodies described inWO2012058592, herein incorporated by reference. In another embodiment,the anti-EGFR antibody is a non-functional antibody, for example,humanized ML66. More specifically, the anti-EGFR antibody is huML66.

The invention further provides a pharmaceutical composition comprisingany of the conjugates described herein, and a pharmaceuticallyacceptable carrier.

The invention additional provides a conjugate comprising any of thesubject compounds linked to a cell-binding agent.

The invention further provides a method of inhibiting abnormal cellgrowth or treating a proliferative disorder, an autoimmune disorder,destructive bone disorder, infectious disease, viral disease, fibroticdisease, neurodegenerative disorder, pancreatitis or kidney disease in amammal comprising administering to the mammal a therapeuticallyeffective amount of any of the compounds (with or without any linkergroup) or conjugates of the invention, and, optionally, a secondchemotherapeutic agent.

In certain embodiments, the second chemotherapeutic agent isadministered to the mammal sequentially or consecutively.

In certain embodiments, the method is for treating a condition selectedfrom cancer, rheumatoid arthritis, multiple sclerosis, graft versus hostdisease (GVHD), transplant rejection, lupus, myositis, infection, andimmune deficiency.

In certain embodiments, the method or conjugate is for treating acancer.

In certain embodiments, the cancer is a hematological cancer or a solidtumor. More specifically, the cancer is ovarian cancer, pancreaticcancer, cervical cancer, melanoma, lung cancer (e.g., non small-celllung cancer (NSCLC)), breast cancer, squamous cell carcinoma of the headand neck, prostate cancer, endometrial cancer, lymphoma (e.g.,non-Hodgkin lymphoma), myelodysplastic syndrome (MDS), peritonealcancer, or leukemia (e.g., acute myeloid leukemia (AML), acute monocyticleukemia, promyelocytic leukemia, eosinophilic leukaemia, acutelymphoblastic leukemia (e.g., B-ALL), chronic lymphocytic leukemia (CLL)and chronic myeloid leukemia (CML)).

Production of Cell-Binding Agent-Drug Conjugates

In order to link the cytotoxic compounds or derivative thereof of thepresent invention to the cell-binding agent, the cytotoxic compound cancomprise a linking moiety with a reactive group bonded thereto, such ascompound 14 (Example 1), 23 (Example 2), 35 (Example 3), 49 (Example 4),80 (Example 5), 90 (Example 6), 63 (Example 7), or 70 (Example 8). Thesecompounds can be directly linked to the cell-binding agent.Representative processes for linking the cytotoxic compounds having areactive group bonded thereof with the cell-binding agent to produce thecell-binding agent-cytotoxic agent conjugates are described in Examples11, 13, 14-17, 19 and 20.

In one embodiment, a bifunctional crosslinking reagent can be firstreacted with the cytotoxic compound to provide the compound bearing alinking moiety with one reactive group bonded thereto (i.e., drug-linkercompound), which can then react with a cell binding agent.Alternatively, one end of the bifunctional crosslinking reagent canfirst react with the cell binding agent to provide the cell bindingagent bearing a linking moiety with one reactive group bonded thereto,which can then react with a cytotoxic compound. The linking moiety cancontain a chemical bond that allows for the release of the cytotoxicmoiety at a particular site. Suitable chemical bonds are well known inthe art and include disulfide bonds, thioether bonds, acid labile bonds,photolabile bonds, peptidase labile bonds and esterase labile bonds (seefor example U.S. Pat. Nos. 5,208,020; 5,475,092; 6,441,163; 6,716,821;6,913,748; 7,276,497; 7,276,499; 7,368,565; 7,388,026 and 7,414,073).Preferred are disulfide bonds, thioether and peptidase labile bonds.Other linkers that can be used in the present invention includenon-cleavable linkers, such as those described in are described indetail in U.S. publication number 2005/0169933, or charged linkers orhydrophilic linkers and are described in US 2009/0274713, US2010/01293140 and WO 2009/134976, each of which is expresslyincorporated herein by reference, each of which is expresslyincorporated herein by reference.

In one embodiment, a solution of a cell-binding agent (e.g., anantibody) in aqueous buffer may be incubated with a molar excess of abifunctional crosslinking agent, such asN-succinimidyl-4-(2-pyridyldithio)pentanoate (SPP),N-succinimidyl-4-(2-pyridyldithio)butanoate (SPDB),N-succinimidyl-4-(2-pyridyldithio)2-sulfo butanoate (sulfo-SPDB) tointroduce dithiopyridyl groups. The modified cell-binding agent (e.g.,modified antibody) is then reacted with the thiol-containing cytotoxiccompound described herein, such as compound 98 or 99 (Examples 9 and10), to produce a disulfide-linked cell-binding agent-cytotoxic agentconjugate of the present invention.

In another embodiment, the thiol-containing cytotoxic compound describedherein, such as compound 98 or 99 can react with a bifunctionalcrosslinking agent such as N-succinimidyl-4-(2-pyridyldithio)pentanoate(SPP), N-succinimidyl-4-(2-pyridyldithio)butanoate (SPDB),N-succinimidyl-4-(2-pyridyldithio)2-sulfo butanoate (sulfo-SPDB) to forma cytotoxic agent-linker compound, which can then react with acell-biding agent to produce a disulfide-linked cell-bindingagent-cytotoxic agent conjugate of the present invention. The cytotoxicagent-linker compound can be prepared in situ without purificationbefore reacting with the cell-binding agent. A representative process isdescribed in Examples 12 and 18. Alternatively, the cytotoxicagent-linker compound can be purified prior to reacting with thecell-binding agent.

The cell binding agent-cytotoxic agent conjugate may be purified usingany purification methods known in the art, such as those described inU.S. Pat. No. 7,811,572 and US Publication No. 2006/0182750, both ofwhich are incorporated herein by reference. For example, thecell-binding agent-cytotoxic agent conjugate can be purified usingtangential flow filtration, adsorptive chromatography, adsorptivefiltration, selective precipitation, non-absorptive filtration orcombination thereof. Preferably, tangential flow filtration (TFF, alsoknown as cross flow filtration, ultrafiltration and diafiltration)and/or adsorptive chromatography resins are used for the purification ofthe conjugates.

Alternatively, the cell-binding agent (e.g., an antibody) may beincubated with a molar excess of an antibody modifying agent such as2-iminothiolane, L-homocysteine thiolactone (or derivatives), orN-succinimidyl-S-acetylthioacetate (SATA) to introduce sulfhydrylgroups. The modified antibody is then reacted with the appropriatedisulfide-containing cytotoxic agent, to produce a disulfide-linkedantibody-cytotoxic agent conjugate. The antibody-cytotoxic agentconjugate may then be purified by methods described above. The cellbinding agent may also be engineered to introduce thiol moieties, suchas cysteine-engineered antibodies disclosed in U.S. Pat. Nos. 7,772,485and 7,855,275.

In another embodiment, a solution of a cell-binding agent (e.g., anantibody) in aqueous buffer may be incubated with a molar excess of anantibody-modifying agent such asN-succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate tointroduce maleimido groups, or withN-succinimidyl-4-(iodoacetyl)-aminobenzoate (SIAB) to introduceiodoacetyl groups. The modified cell-binding agent (e.g., modifiedantibody) is then reacted with the thiol-containing cytotoxic agent toproduce a thioether-linked cell-binding agent-cytotoxic agent conjugate.The conjugate may then be purified by methods described above.

The number of cytotoxic molecules bound per antibody molecule can bedetermined spectrophotometrically by measuring the ratio of theabsorbance at 280 nm and 330 nm. An average of 1-10 cytotoxiccompounds/antibody molecule(s) can be linked by the methods describedherein. The preferred average number of linked cytotoxic compounds perantibody molecule is 2-5, and the most preferred is 2.5-4.0.

Representative processes for preparing the cell-binding agent-drugconjugates of the present invention are described in U.S. Pat. No.8,765,740 and U.S. Application Publication No. 2012/0238731. The entireteachings of these references are incorporated herein by reference.

Cytotoxicity of Compounds and Conjugates

The cytotoxic compounds and cell-binding agent-drug conjugates of theinvention can be evaluated for their ability to suppress proliferationof various cancer cell lines in vitro. For example, cell lines such ashuman cervical carcinoma cell line KB, human acute monocytic leukemiacell line THP-1, human promyelocytic leukemia cell line HL60, humanacute myeloid leukaemia cell line HNT-34, can be used for the assessmentof cytotoxicity of these compounds and conjugates. Cells to be evaluatedcan be exposed to the compounds or conjugates for 1-5 days and thesurviving fractions of cells measured in direct assays by known methods.IC₅₀ values can then be calculated from the results of the assays.Alternatively or in addition, an in vitro cell line sensitivity screen,such as the one described by the U.S. National Cancer Institute (seeVoskoglou-Nomikos et al., 2003, Clinical Cancer Res. 9: 42227-4239,incorporated herein by reference) can be used as one of the guides todetermine the types of cancers that may be sensitive to treatment withthe compounds or conjugates of the invention.

Examples of in vitro potency and target specificity ofantibody-cytotoxic agent conjugates of the present invention are shownin FIGS. 2 and 4. All of the conjugates are extremely cytotoxic on theantigen positive cancer cells with an IC₅₀ in the low picomolar range.Antigen negative cell lines remained viable when exposed to the sameconjugates.

In one example, in vivo efficacy of a cell binding agent/cytotoxic agentconjugate was measured. SCID mice bearing NCI-H2110 tumor cells weretreated with huMov19-80 and huMov19-90 conjugates and significant tumorregression was observed at multiple doses while untreated mice grewtumors rapidly (FIG. 6). Activity for huMov19-90 conjugate was observedat doses as low as 5 μg/kg.

Compositions and Methods of Use

The present invention includes a composition (e.g., a pharmaceuticalcomposition) comprising novel benzodiazepine compounds described herein(e.g., indolinobenzodiazepine or oxazolidinobenzodiazepine), derivativesthereof, or conjugates thereof, (and/or solvates, hydrates and/or saltsthereof) and a carrier (a pharmaceutically acceptable carrier). Thepresent invention also includes a composition (e.g., a pharmaceuticalcomposition) comprising novel benzodiazepine compounds described herein,derivatives thereof, or conjugates thereof, (and/or solvates, hydratesand/or salts thereof) and a carrier (a pharmaceutically acceptablecarrier), further comprising a second therapeutic agent. The presentcompositions are useful for inhibiting abnormal cell growth or treatinga proliferative disorder in a mammal (e.g., human). The presentcompositions are also useful for treating depression, anxiety, stress,phobias, panic, dysphoria, psychiatric disorders, pain, and inflammatorydiseases in a mammal (e.g., human).

The present invention includes a method of inhibiting abnormal cellgrowth or treating a proliferative disorder in a mammal (e.g., human)comprising administering to said mammal a therapeutically effectiveamount of novel benzodiazepine compounds described herein (e.g.,indolinobenzodiazepine or oxazolidinobenzodiazepine), derivativesthereof, or conjugates thereof, (and/or solvates and salts thereof) or acomposition thereof, alone or in combination with a second therapeuticagent.

The present invention also provides methods of treatment comprisingadministering to a subject in need of treatment an effective amount ofany of the conjugates described above.

Similarly, the present invention provides a method for inducing celldeath in selected cell populations comprising contacting target cells ortissue containing target cells with an effective amount of a cytotoxicagent comprising any of the cytotoxic compound-cell-binding agents(e.g., indolinobenzodiazepine or oxazolidinobenzodiazepine dimer linkedto a cell binding agent) of the present invention, a salt or solvatethereof. The target cells are cells to which the cell-binding agent canbind.

If desired, other active agents, such as other anti-tumor agents, may beadministered along with the conjugate.

Suitable pharmaceutically acceptable carriers, diluents, and excipientsare well known and can be determined by those of ordinary skill in theart as the clinical situation warrants.

Examples of suitable carriers, diluents and/or excipients include: (1)Dulbecco's phosphate buffered saline, pH about 7.4, containing or notcontaining about 1 mg/mL to 25 mg/mL human serum albumin, (2) 0.9%saline (0.9% w/v NaCl), and (3) 5% (w/v) dextrose; and may also containan antioxidant such as tryptamine and a stabilizing agent such as Tween20.

The method for inducing cell death in selected cell populations can bepracticed in vitro, in vivo, or ex vivo.

Examples of in vitro uses include treatments of autologous bone marrowprior to their transplant into the same patient in order to killdiseased or malignant cells: treatments of bone marrow prior to theirtransplantation in order to kill competent T cells and preventgraft-versus-host-disease (GVHD); treatments of cell cultures in orderto kill all cells except for desired variants that do not express thetarget antigen; or to kill variants that express undesired antigen.

The conditions of non-clinical in vitro use are readily determined byone of ordinary skill in the art.

Examples of clinical ex vivo use are to remove tumor cells or lymphoidcells from bone marrow prior to autologous transplantation in cancertreatment or in treatment of autoimmune disease, or to remove T cellsand other lymphoid cells from autologous or allogenic bone marrow ortissue prior to transplant in order to prevent GVHD. Treatment can becarried out as follows. Bone marrow is harvested from the patient orother individual and then incubated in medium containing serum to whichis added the cytotoxic agent of the invention, concentrations range fromabout 10 μM to 1 pM, for about 30 minutes to about 48 hours at about 37°C. The exact conditions of concentration and time of incubation, i.e.,the dose, are readily determined by one of ordinary skill in the art.After incubation the bone marrow cells are washed with medium containingserum and returned to the patient intravenously according to knownmethods. In circumstances where the patient receives other treatmentsuch as a course of ablative chemotherapy or total-body irradiationbetween the time of harvest of the marrow and reinfusion of the treatedcells, the treated marrow cells are stored frozen in liquid nitrogenusing standard medical equipment.

For clinical in vivo use, the cytotoxic agent of the invention will besupplied as a solution or a lyophilized powder that are tested forsterility and for endotoxin levels. Examples of suitable protocols ofconjugate administration are as follows. Conjugates are given weekly for4 weeks as an intravenous bolus each week. Bolus doses are given in 50to 1000 mL of normal saline to which 5 to 10 mL of human serum albumincan be added. Dosages will be 10 μg to 2000 mg per administration,intravenously (range of 100 ng to 20 mg/kg per day). After four weeks oftreatment, the patient can continue to receive treatment on a weeklybasis. Specific clinical protocols with regard to route ofadministration, excipients, diluents, dosages, times, etc., can bedetermined by one of ordinary skill in the art as the clinical situationwarrants.

Examples of medical conditions that can be treated according to the invivo or ex vivo methods of inducing cell death in selected cellpopulations include malignancy of any type including, for example,cancer, autoimmune diseases, such as systemic lupus, rheumatoidarthritis, and multiple sclerosis; graft rejections, such as renaltransplant rejection, liver transplant rejection, lung transplantrejection, cardiac transplant rejection, and bone marrow transplantrejection; graft versus host disease; viral infections, such as CMVinfection, HIV infection, AIDS, etc.; and parasite infections, such asgiardiasis, amoebiasis, schistosomiasis, and others as determined by oneof ordinary skill in the art.

Cancer therapies and their dosages, routes of administration andrecommended usage are known in the art and have been described in suchliterature as the Physician's Desk Reference (PDR). The PDR disclosesdosages of the agents that have been used in treatment of variouscancers. The dosing regimen and dosages of these aforementionedchemotherapeutic drugs that are therapeutically effective will depend onthe particular cancer being treated, the extent of the disease and otherfactors familiar to the physician of skill in the art and can bedetermined by the physician. The contents of the PDR are expresslyincorporated herein in its entirety by reference. One of skill in theart can review the PDR, using one or more of the following parameters,to determine dosing regimen and dosages of the chemotherapeutic agentsand conjugates that can be used in accordance with the teachings of thisinvention. These parameters include:

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Analogues and Derivatives

One skilled in the art of cytotoxic agents will readily understand thateach of the cytotoxic agents described herein can be modified in such amanner that the resulting compound still retains the specificity and/oractivity of the starting compound. The skilled artisan will alsounderstand that many of these compounds can be used in place of thecytotoxic agents described herein. Thus, the cytotoxic agents of thepresent invention include analogues and derivatives of the compoundsdescribed herein.

All references cited herein and in the examples that follow areexpressly incorporated by reference in their entireties.

EXAMPLES

The invention will now be illustrated by reference to non-limitingexamples. Unless otherwise stated, all percents, ratios, parts, etc. areby weight. All reagents were purchased from the Aldrich Chemical Co.,New Jersey, or other commercial sources. Nuclear Magnetic Resonance (¹HNMR) spectra were acquired on a Bruker 400 MHz instrument. Mass spectrawere acquired on a Bruker Daltonics Esquire 3000 instrument and LCMSwere acquired on an Agilent 1260 Infinity LC with an Agilent 6120 singlequadropole MS using electrospray ionization.

The following solvents, reagents, protecting groups, moieties and otherdesignations may be referred to by their abbreviations in parenthesis:

-   Me=methyl; Et=ethyl; Pr=propyl; i-Pr=isopropyl; Bu=butyl;    t-Bu=tert-butyl; Ph=phenyl, and Ac=acetyl-   AcOH or HOAc=acetic acid-   ACN or CH₃CN=acetonitrile-   Ala=alanine-   aq=aqueous-   BH₃.DMS=borane dimethylsulfide complex-   Bn=benzyl-   Boc or BOC=tert-butoxycarbonyl-   CBr₄=carbontetrabromide-   Cbz or Z=benzyloxycarbonyl-   DCM or CH₂Cl₂=dichloromethane-   DCE=1,2-dichloroethane-   DMAP=4-dimethylaminopyridine-   DI water=deionized water-   DIBAL=diisobutylaluminum hydride-   DIEA or DIPEA=N,N-diisopropylethylamine-   DMA=N,N-dimethylacetamide-   DMF=N,N-dimethylformamide-   DMSO=dimethyl sulfoxide-   DTT=dithiothreitol-   EDC=1-ethyl-3-(3-dimethylaminopropyl)carbodiimide-   EEDQ=N-Ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline-   ESI or ES=electrospray ionization-   EtOAc=ethylacetate-   Gly=glycine-   g=grams-   h=hour-   HATU=N,N,N′N′-tetramethyl-O-(7-azabenzotriazol-1-yl)uronium    hexaphosphate-   HPLC=high-performance liquid chromatography-   HOBt or HOBT=1-hydroxybenzotriazole-   LAH=lithium aluminum hydride-   LC=liquid chromatography-   LCMS=liquid chromatography mass spectrometry-   min=minutes-   mg=miligrams-   mL=mililiters-   mmol=milimoles-   μg=micrograms-   μL=microliters-   μmol=micromoles-   Me=methyl-   MeOH=methanol-   MeI=methyliodide-   MS=mass spectrometry-   MsCl=methanesulfonyl chloride (mesyl chloride)-   Ms₂O=methanesulfonic anhydride-   NaBH(OAc)₃=sodium triacetoxyborohydride-   NHS=N-hydroxysuccinamide-   NMR=nuclear magnetic resonance spectroscopy-   PPh₃=triphenylphosphine-   PTLC=preparative thin layer chromatography-   rac=racemic mixture-   R_(f)=retardation factor-   RPHPLC or RP-HPLC=reverse phase high-performance liquid    chromatography-   RT or rt=room temperature (ambient, about 25° C.)-   sat or sat'd=saturated-   STAB=sodium triacetoxyborohydride (NaBH(OAc)₃)-   TBSCl or TBDMSCl=tert-butyldimethylsilyl chloride-   TBS=tert-butyldimethylsilyl-   TCEP.HCl=tris(2-carboxyethyl)phosphine hydrochloride salt-   TEA=triethylamine (Et₃N)-   TFA=trifluoroacetic acid-   THF=tetrahydrofuran-   TLC=thin layer chromatography-   Val=valine

Example 1. Synthesis of 2,5-dioxopyrrolidin-1-yl6-((2-((2-((2-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-2-oxoethyl)amino)-2-oxoethyl)amino)-2-oxoethyl)amino)-6-oxohexanoate(Compound 14)

Step 1:

Z-Gly-Gly-OH compound 1 (5.0 g, 18.78 mmol) and H-Gly-Ot-Bu.HCl compound2 (3.46 g, 20.66 mmol) were dissolved in DMF (37.6 mL). EDC.HCl (3.96 g,20.66 mmol) and HOBt (2.88 g, 18.78 mmol) were added to the reactionflask, followed by DIPEA (8.18 mL, 46.9 mmol). The reaction was stirredat rt under Ar overnight. The reaction mixture was diluted with CH₂Cl₂,washed with sat'd NH₄Cl, sat'd NaHCO₃, followed by water and brine. Theorganic layer was dried over Na₂SO₄, filtered and concentrated. Thecrude product was purified by silica gel flash chromatography (MeOH/DCM,gradient, 0% to 5%) to yield pure compound 3 as a white solid (6.35 g,89% yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.18-8.13 (m, 2H), 7.48 (t, 1H,J=6.0 Hz), 7.37-7.36 (m, 3H), 7.34-7.32 (m, 1H), 5.04 (s, 2H), 4.09 (q,1H, J=5.2 Hz), 3.74 (t, 4H, J=6.1 Hz), 3.67 (d, 2H, J=6.0 Hz), 3.17 (d,2H, J=5.2 Hz), 1.41 (s, 9H). LCMS=4.28 min (8 min method). Mass observed(ESI⁺): 324.15 (M-t-Bu+H).

Step 2:

Compound 3 (6.3 g, 16.60 mmol) was dissolved in MeOH (52.7 mL) and water(2.64 mL). The reaction mixture was purged with Ar and was degassed for5 min. Pd/C (wet, 10%) (0.884 g, 0.830 mmol) was slowly added. Thenbubbled in H₂ from a balloon for 1 min. The reaction was stirred under aballoon of H₂ at rt overnight. The reaction mixture was filtered throughCelite and the filter cake was washed with MeOH (30 mL) and wasconcentrated. CH₃CN (20 mL) was added to the residue and wasconcentrated. This was repeated 2 more times to obtain a sticky solid.The residue was slurried in EtOAc/hexanes (2:1, 50 mL) and filtered andwas rinsed with EtOAc/hexanes (1:1, 30 mL). The solid was dried undervacuum/N₂ for 1 h to obtain compound 4 as a white solid (3.66 g, 90%yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.21-8.18 (m, 1H), 8.12 (bs, 1H),3.76 (bs, 2H), 3.73 (d, 2H, J=6.0 Hz), 3.13 (s, 2H), 1.93 (bs, 2H), 1.41(s, 9H).

Step 3:

Amine compound 4 (1.0 g, 4.08 mmol) and mono methyladipate (664 μL, 4.48mmol) were dissolved in DMF (13.59 mL). EDC.HCl (860 mg, 4.48 mmol) andHOBt (624 mg, 4.08 mmol) were added to the reaction mixture, followed byDIEA (1.424 mL, 8.15 mmol). The reaction was stirred at rt overnight.The reaction mixture was diluted with DCM/MeOH (20 mL, 5:1) and waswashed with sat'd NH₄Cl, sat'd NaHCO₃, water and brine. The organiclayer was dried over Na₂SO₄, filtered and concentrated. The crudeproduct was purified by silica gel flash chromatography (gradient, 0% to20% MeOH/DCM) to obtain pure compound 5 as a white solid (1.5 g, 95%yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.17-8.06 (m, 3H), 3.74-3.71 (m,6H), 3.59 (s, 3H), 2.32 (bt, 2H, J=6.9 Hz), 2.14 (bt, 2H, J=6.7 Hz),1.52-1.49 (m, 4H), 1.41 (s, 9H).

Step 4:

Compound 5 (1.5 g, 3.87 mmol) was stirred in TFA (5.97 mL, 77.0 mmol)and deionized water (300 μL) at rt overnight. CH₃CN (10 mL) was added tothe reaction mixture and was stirred for 5 min. The mixture became thickwith lots of white precipitate. More CH₃CN (30 mL) was added and wasfurther stirred for 5 min. The mixture was filtered and dried undervacuum/N₂ for 1 h to obtain pure compound 6 as a white solid (0.7 g, 55%yield). ¹H NMR (400 MHz, DMSO-d6): δ 12.56 (s, 1H), 8.16-8.06 (m, 3H),3.73 (dt, 6H, J=8.6, 6.1 Hz), 3.59 (s, 3H), 2.32-2.29 (m, 2H), 2.16-2.13(m, 2H), 1.51 (bt, 4H, J=3.5 Hz).

Step 5:

Aniline compound 7 (100 mg, 0.653 mmol) and acid compound 6 (227 mg,0.685 mmol) were suspended in CH₂Cl₂/MeOH (4.35 mL/2.2 mL) at rt. EEDQ(323 mg, 1.306 mmol) was added and the reaction was stirred at rtovernight. The solvent was concentrated and the residue was slurried inEtOAc (15 mL) and filtered. The solids were washed with EtOAc (2×15 mL)and was dried under vacuum/N₂ to obtain compound 8 as a white solid (260mg, 85% yield). ¹H NMR (400 MHz, DMSO-d6): δ 9.74 (s, 1H), 8.21-8.19 (m,2H), 8.11-8.08 (m, 1H), 7.45 (s, 2H), 6.96 (s, 1H), 5.17 (t, 2H, J=5.7Hz), 4.45 (d, 4H, J=5.6 Hz), 3.87 (d, 2H, J=5.8 Hz), 3.75 (dd, 4H,J=5.7, 13.4 Hz), 3.58 (s, 3H), 2.31-2.27 (m, 2H), 2.16-2.13 (m, 2H),1.52-1.48 (m, 4H). LCMS=0.886 min (15 min method). Mass observed (ESI⁺):489.3 (M+Na).

Step 6:

Diol compound 8 (260 mg, 0.557 mmol) and carbontetrabromide (555 mg,1.672 mmol) were dissolved in DMF (5.57 mL). Triphenylphosphine (439 mg,1.672 mmol) was added and the brown mixture was stirred under Ar at rtfor 4 h. The reaction mixture was diluted with DCM/MeOH (10:1, 30 mL)and was washed with water and brine. The organic layer was dried overNa₂SO₄, filtered and concentrated. The crude residue was purified bysilica gel flash chromatography (MeOH/DCM, 0% to 10%, gradient) toobtain compound 9 as a yellow solid. The product was slurried inCH₂Cl₂/EtOAc (1:10, 30 mL) and then filtered. The solid was washed withEtOAc and was dried under vacuum/N₂ to obtained pure compound 9 as anoff white solid (170 mg, 52% yield). ¹H NMR (400 MHz, DMSO-d6): δ 9.95(s, 1H), 8.25-8.20 (m, 2H), 8.12-8.10 (m, 1H), 7.65 (s, 2H), 7.22 (s,1H), 4.68 (s, 3H), 3.89 (d, 2H, J=5.8 Hz), 3.77 (dd, 4H, J=5.7, 7.4 Hz),3.58 (s, 3H), 2.31-2.27 (m, 2H), 2.16-2.13 (m, 2H), 1.51-1.49 (m, 4H).LCMS=3.335 min (15 min method). Mass observed (ESI⁺): 593.2 (M+H).

Step 7:

Dibromide compound 9 (109 mg, 0.184 mmol) and IGN monomer compound 10(119 mg, 0.405 mmol) were dissolved in DMF (1.84 mL). Potassiumcarbonate (63.6 mg, 0.460 mmol) was added and was stirred at rtovernight. Water (20 mL) was added to the reaction mixture toprecipitate the product. The slurry was stirred at rt for 5 min and wasthen filtered and dried under vacuum/N₂ for 1 h. The crude product waspurified by silica gel flash chromatography (MeOH/CH₂Cl₂, gradient, 0%to 5%) to obtain compound 11 as a yellow solid (160 mg, 60% yield, 70%purity). LCMS=5.240 min (15 min method). Mass observed (ESI⁺): 1019.7(M+H).

Step 8:

Diimine compound 11 (140 mg, 0.11 mmol) was dissolved in1,2-dichloroethane (1.1 mL). NaBH(OAc)₃ (23.29 mg, 0.11 mmol) was addedto the reaction mixture and was stirred at rt for 1 h. The reaction wasdiluted with CH₂Cl₂ (30 mL) and was quenched with sat'd aq NH₄Clsolution (15 mL). The layers were separated and was washed with brine,dried over Na₂SO₄ and concentrated. The crude residue was purified byRPHPLC (C18 column, CH₃CN/H₂O, gradient, 35% to 55%) to yield mono iminecompound 12 as a white fluffy solid (33 mg, 29% yield) and startingmaterial compound 11 was also recovered (25 mg). LCMS=7.091 min (15 minmethod). Mass observed (ESI⁺): 1021.7 (M+H).

Step 9:

Methylester compound 12 (33 mg, 0.029 mmol) was dissolved in THF (1.09mL) and water (364 μL). LiOH (6.97 mg, 0.291 mmol) was added and thereaction was stirred at rt for 1.5 h. The reaction mixture was dilutedwith H₂O (5 mL) and acidified with 0.5 M aq HCl until pH-4. The aqueouslayer was extracted with CH₂Cl₂/MeOH (3:1, 3×20 mL). The combinedorganic layers were dried over Na₂SO₄, filtered and concentrated toobtain crude compound 13 as a yellow solid (29 mg, 99% yield).LCMS=5.356 min (15 min method). Mass observed (ESI⁺): 1007.7 (M+H).

Step 10:

EDC.HCl (22.08 mg, 0.115 mmol) was added to a stirred solution of acidcompound 13 (29 mg, 0.023 mmol) and N-hydroxysuccinamide (21.21 mg,0.184 mmol) in CH₂Cl₂ (2.3 mL) at rt. The reaction mixture was stirredfor 2 h. The reaction mixture was diluted with CH₂Cl₂ and was washedwith water (1×15 mL) and brine (1×15 mL). The organic layer was driedover Na₂SO₄, filtered and concentrated. The crude product was purifiedby RPHPLC (C18 column, CH₃CN/H₂O, gradient, 35% to 55%). Fractionscontaining product were combined and lyophilized to obtain2,5-dioxopyrrolidin-1-yl6-((2-((2-((2-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methylphenyl)amino)-2-oxoethyl)amino)-2-oxoethyl)amino)-2-oxoethyl)amino)-6-oxohexanoate,compound 14 as a white fluffy solid (8 mg, 31% yield). LCMS=5.867 min(15 min method). Mass observed (ESI⁺): 1104.7 (M+H).

Example 2. Synthesis of (1r,4r)-2,5-dioxopyrrolidin-1-yl4-((2-((2-((2-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-2-oxoethyl)amino)-2-oxoethyl)amino)-2-oxoethyl)carbamoyl)cyclohexane-carboxylate,(Compound 23)

Step 1:

Amine compound 4 (200 mg, 0.815 mmol) and1,4-trans-cyclohexanedicarboxlic acid monomethylester compound 15 (182mg, 0.978 mmol) were dissolved in DMF (2.72 mL). EDC.HCl (188 mg, 0.978mmol) and HOBt (125 mg, 0.815 mmol) were added to the reaction mixture,followed by DIEA (285 μL, 1.631 mmol). The mixture was stirred at rtovernight. The reaction mixture was diluted with CH₂Cl₂ and washed withsat'd NH₄Cl, sat'd NaHCO₃, brine, and water. The organic layer was driedover Na₂SO₄ and concentrated to a sticky residue. CH₃CN (15 mL) wasadded to the residue and was concentrated. This was repeated 2 moretimes to obtain compound 16 as a dry white powder (300 mg, 85% yield).¹H NMR (400 MHz, DMSO-d6): δ 8.16 (t, 1H, J=5.9 Hz), 8.04 (dt, 2H,J=5.6, 14.8 Hz), 3.74-3.69 (m, 6H), 3.59 (s, 3H), 2.31-2.25 (m, 1H),2.20-2.13 (m, 1H), 1.94-1.91 (m, 2H), 1.82-1.79 (m, 2H), 1.41 (s, 9H),1.34 (d, 3H, J=11.7 Hz).

Step 2:

TFA (1.40 mL, 18.14 mmol) and DI water (67.8 μL) were added to neatcompound 16 (300 mg, 0.726 mmol) at rt and was stirred for 3 h. CH₃CN(20 mL) was added to the reaction mixture and was concentrated. This wasrepeated this two more times to obtain compound 17 as a white solid (230mg, 89% yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.16-8.13 (m, 1H),8.07-8.01 (m, 2H), 3.76-3.73 (m, 4H), 3.70 (bd, 2H, J=5.1 Hz), 3.59 (s,3H), 2.31-2.25 (m, 1H), 2.19-2.14 (m, 1H), 1.94-1.91 (m, 2H), 1.82-1.79(m, 2H), 1.42-1.26 (m, 4H).

Step 3:

Aniline compound 7 (135 mg, 0.881 mmol) and acid compound 17 (331 mg,0.925 mmol) were suspended in CH₂Cl₂/MeOH (2.9 mL/1.5 mL) at rt. EEDQ(436 mg, 1.763 mmol) was added and the reaction was stirred at rtovernight. The solvent was concentrated and the residue was slurried inEtOAc (15 mL) and filtered. The solids were washed with EtOAc (2×15 mL)and was dried under vacuum/N₂ to obtain compound 18 as a white solid(330 mg, 61% yield). ¹H NMR (400 MHz, DMSO-d6): δ 9.73 (s, 1H), 8.18(dt, 2H, J=6.0, 19.2 Hz), 8.09-8.01 (m, 2H), 7.45 (s, 2H), 6.96 (s, 1H),5.17 (t, 2H, J=5.7 Hz), 4.45 (d, 4H, J=5.6 Hz), 3.88-3.84 (m, 3H),3.77-3.69 (m, 8H), 3.63 (s, 2H), 3.59 (s, 6H), 2.30-2.22 (m, 2H),2.19-2.13 (m, 2H), 1.94-1.90 (m, 4H), 1.82-1.78 (m, 4H), 1.41-1.26 (m,8H).

Step 4:

Compound 18 (330 mg, 0.536 mmol) and CBr₄ (533 mg, 1.608 mmol) weredissolved in DMF (5.36 mL). PPh₃ (422 mg, 1.608 mmol) was added to thereaction mixture, at which point the reaction turned yellow with aslight exotherm. The reaction was stirred under Ar for 4 h. The reactionmixture was diluted with CH₂Cl₂ and was washed with water and brine. Theorganic layer was dried over Na₂SO₄ and concentrated. The crude residuewas purified by silica gel flash chromatography (MeOH/CH₂Cl₂, gradient,0% to 10%) to obtain compound 19 as a white solid (234 mg, 64% yield).LCMS=4.453 min (8 min method). Mass observed (ESI⁺): 617.10 (M+H).

Step 5:

Compound 20 was prepared similarly as compound 11 in Example 1. Compound20 was obtained as a yellow solid after purification (264 mg, 60%yield). LCMS=4.831 min (8 min method). Mass observed (ESI⁺): 1045.20(M+H).

Step 6:

Compound 21 was prepared similarly as compound 12 in Example 1. Compound21 was obtained as a white solid after C18 purification (51 mg, 31%yield). LCMS=5.127 min (8 min method). Mass observed (ESI⁺): 1047.30(M+H).

Step 7:

Methylester compound 21 (48 mg, 0.046 mmol) was dissolved in1,2-dichloroethane (3.06 mL). Trimethylstannanol (124 mg, 0.688 mmol)was added to the reaction mixture and was heated at 80° C. overnight.The reaction mixture was cooled to rt and was diluted with water (15mL). The aqueous layer was acidified to pH ˜4 with 1 M HCl. The mixturewas extracted with CH₂Cl₂/MeOH (10:1, 3×20 mL). The combined organiclayers were washed with brine and was dried over Na₂SO₄ andconcentrated. The crude residue was plugged through a short pad ofsilica gel and was flushed with CH₂Cl₂/MeOH (10:1, then 5:1, 2×30 mL)and was concentrated. Acid compound 22 was obtained as a yellow solidand was used in the next step without further purification (48 mg, 100%yield). LCMS=5.338 min (15 min method). Mass observed (ESI⁺): 1033.7(M+H).

Step 8:

Compound 23 was prepared similarly as compound 13 in Example 1.(1r,4r)-2,5-dioxopyrrolidin-1-yl4-((2-((2-((2-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-2-oxoethyl)amino)-2-oxoethyl)amino)-2-oxoethyl)carbamoyl)cyclohexanecarboxylate,compound 23 was obtained as a white solid after C18 purification (8 mg,19% yield). LCMS=6.007 min (15 min method). Mass observed (ESI⁺): 1130.8(M+H).

Example 3. Synthesis of 2,5-dioxopyrrolidin-1-yl6-(((S)-1-(((S)-1-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-1-oxopropan-2-yl)amino)-3-methyl-1-oxobutan-2-yl)amino)-6-oxohexanoate(Compound 35)

Step 1:

Z-Val-OH compound 24 (3.0 g, 11.94 mmol) and L-Ala-OtBu compound 25(1.907 g, 13.13 mmol) were dissolved in DMF (23.88 mL). EDC.HCl (2.52 g,13.13 mmol) and HOBt (2.011 g, 13.13 mmol) were added to the reactionmixture, followed by DIEA (4.59 mL, 26.3 mmol). The reaction was stirredreaction at rt overnight under Ar. The reaction mixture was diluted withCH₂Cl₂ and was washed with sat'd NaHCO₃, sat'd NH₄Cl, water and brine.The organic layer was dried over Na₂SO₄, filtered and concentrated. Thecrude residue was purified by silica gel flash chromatography(EtOAc/hexanes, gradient, 0% to 50%) to obtain compound 26 as a whitesolid (3.68 g, 81% yield). ¹H NMR (400 MHz, CDCl₃): δ 7.39-7.29 (m, 5H),6.29 (bd, 1H, J=6.9 Hz), 5.34 (bd, 1H, J=8.4 Hz), 5.11 (s, 2H), 4.45 (p,1H, J=7.2 Hz), 4.02-3.98 (m, 1H), 2.18-2.09 (m, 1H), 1.56 (s, 9H), 1.37(d, 3H, J=7.0 Hz), 0.98 (d, 3H, J=6.8 Hz), 0.93 (d, 3H, J=6.8 Hz).LCMS=5.571 min (8 min method). Mass observed (ESI⁺): 323.25 (M-tBu+H).

Step 2:

Compound 26 (3.68 g, 9.72 mmol) was dissolved in MeOH (30.9 mL) andwater (1.543 mL). The solution was purged with Ar and was degassed for 5min. Pd/C (10%, wet, 0.517 g) was added slowly to the reaction mixture.H₂ was then bubbled in for a minute. Bubbling was discontinued and thereaction was then stirred under a H₂ balloon overnight. The reactionmixture was filtered through Celite and the filter cake was washed withMeOH (30 mL) and was concentrated to obtain compound 27 as a white solid(2.35 g, 99% yield). ¹H NMR (400 MHz, CDCl₃): δ 7.79-7.77 (m, 1H), 4.50(p, 1H, J=7.3 Hz), 3.27 (d, 1H, J=3.9 Hz), 2.34-2.26 (m, 1H), 1.49 (s,9H), 1.40 (d, 3H, J=7.1 Hz), 1.01 (d, 3H, J=7.0 Hz), 0.86 (d, 3H, J=6.9Hz).

Step 3:

Amine compound 27 (2.35 g, 9.62 mmol) and mono methyladipate (1.69 g,10.58 mmol) were dissolved in DMF (32.1 mL). EDC.HCl (1.94 g, 10.10mmol) and HOBt (1.47 g, 9.62 mmol) were added to the reaction mixture,followed by DIEA (3.36 mL, 19.24 mmol). The reaction was stirred at rtovernight. The reaction mixture was diluted with DCM/MeOH (20 mL, 5:1)and was washed with sat'd NH₄Cl, sat'd NaHCO₃, water and brine. Theorganic layer was dried over Na₂SO₄, filtered and concentrated. Thecrude product was purified by silica gel flash chromatography(EtOAc/hexanes, gradient, 0% to 50%) to obtain compound 28 as a whitesolid (2.77 g, 75% yield). ¹H NMR (400 MHz, CDCl₃): δ 6.29 (d, 1H, J=7.2Hz), 6.12 (d, 1H, J=8.6 Hz), 4.43 (p, 1H, J=7.2 Hz), 4.27 (dd, 1H,J=6.4, 8.6 Hz), 3.66 (s, 3H), 2.35-2.31 (m, 2H), 2.26-2.23 (m, 2H),2.12-2.03 (m, 1H), 1.70-1.63 (m, 4H), 1.46 (s, 9H), 1.36 (d, 3H, J=7.1Hz), 0.95 (apparent t, 6H, J=6.6 Hz).

Step 4:

TFA (8.28 mL, 108.0 mmol) and water (0.56 mL) were added to neatcompound 28 (2.77 g, 7.17 mmol) at rt and was stirred for 2.5 h. CH₃CN(30 mL) was added to the reaction mixture and was concentrated. This wasrepeated 2 more times to obtain compound 29 as a pale yellow solid (2.0g, 84% yield). ¹H NMR (400 MHz, CDCl₃): δ 8.11 (bs, 1H), 7.29 (d, 1H,J=8.9 Hz), 7.14 (d, 1H, 6.8 Hz), 4.58 (p, 1H, J=7.1 Hz), 4.37 (t, 1H,J=8.7 Hz), 3.68 (s, 3H), 2.37-2.32 (m, 4H), 2.03-1.99 (m, 2H), 1.69-1.63(m, 4H), 1.49 (d, 3H, J=7.2 Hz), 0.97 (d, 3H, J=4.8 Hz), 0.96 (d, 3H,J=4.8 Hz).

Step 5:

Aniline compound 7 (150 mg, 0.98 mmol) and acid compound 29 (340 mg,1.03 mmol) were suspended in CH₂Cl₂/MeOH (3.26 mL, 1.62 mL) at rt. EEDQ(484 mg, 1.96 mmol) was added and the reaction was stirred at rtovernight. The solvent was concentrated and the residue was slurried inEtOAc/Et₂O (15 mL, 15 mL) and filtered. The solids were washed with Et₂O(2×15 mL) and was dried under vacuum/N₂ to obtain compound 30 as a whitesolid (150 mg, 33% yield). ¹H NMR (400 MHz, CDCl₃): δ 7.61 (s, 2H), 7.47(d, 1H, J=7.1 Hz), 7.14 (s, 1H), 6.64 (d, 1H, J=8.0 Hz), 4.82-4.75 (m,1H), 4.45-4.40 (m, 4H), 3.64 (s, 3H), 2.36-2.27 (m, 4H), 2.16-2.07 (m,1H), 1.68-1.59 (m, 4H), 1.47 (d, 3H, J=7.0 Hz), 0.98 (d, 3H, J=3.6 Hz),0.95 (d, 3H, J=4.8 Hz). LCMS=3.073 min (8 min method). Mass observed(ESI⁺): 466.25 (M+H).

Step 6:

Diol compound 30 (150 mg, 0.322 mmol) and CBr₄ (321 mg, 0.967 mmol) weredissolved in DMF (3222 μl). PPh₃ (254 mg, 0.967 mmol) was added to thereaction mixture, at which point the reaction turned red-pink with aslight exotherm. The reaction was stirred under Ar for 4 h. The reactionmixture was diluted with CH₂Cl₂ and was washed with water and brine. Theorganic layer was dried over Na₂SO₄ and concentrated. The crude residuewas purified by silica gel flash chromatography (EtOAc/hexanes,gradient, 0% to 100%) to obtain compound 31 as an off white solid (473mg, 75% yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.19 (d, 1H, J=6.6 Hz),7.85 (d, 1H, J=8.5 Hz), 7.64 (s, 2H), 7.21 (s, 1H), 4.68 (s, 3H), 4.37(p, 1H, J=7.0 Hz), 4.18 (dd, 1H, J=7.2, 8.4 Hz), 3.58 (s, 3H), 2.32-2.29(m, 2H), 2.33-2.12 (m, 2H), 2.01-1.91 (m, 1H), 1.53-1.49 (m, 4H), 1.31(d, 3H, J=7.1 Hz), 0.89 (d, 3H, J=6.8 Hz), 0.85 (d, 3H, J=6.8 Hz).LCMS=5.259 min (8 min method). Mass observed (ESI⁺): 592.05 (M+H).

Step 7:

Compound 32 was prepared similarly as compound 11 in Example 1. Compound32 was obtained as a yellow solid after purification (162 mg, 57% yield,70% purity). LCMS=6.461 min (15 min method). Mass observed (ESI⁺):1018.7 (M+H).

Step 8:

Compound 33 was prepared similarly as compound 12 in Example 1. Compound33 was obtained as a white solid after C18 purification (40 mg, 31%yield). LCMS=5.528 min (8 min method) Mass observed (ESI⁺): 1020.30(M+H).

Step 9:

Compound 34 was prepared similarly as compound 22 in Example 2. Compound34 was obtained as a yellow solid after silica plug (38 mg, 100% yield).LCMS=5.211 min (8 min method). Mass observed (ESI⁺): 1006.35 (M+H).

Step 10:

Compound 35 was prepared similarly as compound 14 in Example 1.2,5-dioxopyrrolidin-1-yl6-(((S)-1-(((S)-1-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-1-oxopropan-2-yl)amino)-3-methyl-1-oxobutan-2-yl)amino)-6-oxohexanoate,compound 35 was obtained as a white solid after C18 purification (8 mg,20% yield). LCMS=7.031 min (15 min method). Mass observed (ESI⁺): 1103.7(M+H).

Example 4. Synthesis of 2,5-dioxopyrrolidin-1-yl2-(3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)-3,6,9,12-tetraoxo-2,5,8,11-tetraazaheptadecan-17-oate(Compound 49)

Step 1:

(5-amino-1,3-phenylene)dimethanol compound 7 (5.0 g, 32.6 mmol) wasdissolved in THF (65.3 mL). TBSCl (12.30 g, 82 mmol) and imidazole (6.67g, 98 mmol) were added and was stirred at rt overnight under Ar. Thereaction mixture was diluted with EtOAc and was washed with sat'd NH₄Cland brine, dried over Na₂SO₄ and concentrated. The crude residue waspurified by silica gel flash chromatography (EtOAc/hexanes, gradient, 0%to 30%) to obtain compound 37 as a yellow oil (13 g, 100% yield). ¹H NMR(400 MHz, CDCl₃): δ 6.71 (s, 1H), 6.60 (s, 2H), 4.65 (s, 4H), 0.94 (s,18H), 0.10 (s, 12H).

Step 2:

Cs₂CO₃ (8.54 g, 26.2 mmol) was added to a stirred solution of anilinecompound 37 (10 g, 26.2 mmol) in DMF (52.4 mL). Methyliodide (1.474 mL,23.58 mmol) was added and the reaction was stirred at rt for 3 h. Water(10 mL) and EtOAc (30 mL) were added to the reaction mixture. The layerswere separated and was extracted with EtOAc (2×). The organic layerswere washed with water (4×), dried over Na₂SO₄, filtered andconcentrated. The crude residue was purified by silica gel flashchromatography (EtOAc/hexanes, gradient, 0% to 10%) to obtain thedesired mono-methylated product compound 38 (3.8 g, 37% yield). ¹H NMR(400 MHz, CDCl₃): δ 6.63 (s, 1H), 6.52 (s, 2H), 4.67 (s, 4H), 2.84 (s,3H), 0.94 (s, 18H), 0.10 (s, 12H).

Step 3:

Aniline compound 38 (1.0 g, 2.53 mmol) and Z-Gly-OH (0.582 g, 2.78 mmol)were dissolved in DMF (8.42 mL). EDC.HCl (1.21 g, 6.32 mmol) and DMAP(340 mg, 2.78 mmol) were added to the reaction mixture and was heated at80° C. overnight. The reaction mixture was diluted with EtOAc and waswashed sat'd NaHCO₃ and water (2×), dried over Na₂SO₄, filtered andconcentrated. The crude residue was purified by silica gelchromotography (EtOAc/hexanes, gradient, 0% to 30% to 100%) to obtaincompound 39 as a yellow sticky solid (780 mg, 53% yield). ¹H NMR (400MHz, CDCl₃): δ 7.27 (m, 6H), 6.90 (s, 2H), 4.94 (s, 2H), 4.62 (s, 4H),3.58 (s, 2H), 3.16 (s. 3H), 0.83 (s, 18H), 0.00 (s, 12H).

Step 4:

Compound 39 (1.26 g, 2.147 mmol) was dissolved in MeOH (6.82 mL) and THF(6.8 mL) and the solution was purged with N₂. Pd/C (10%, 0.228 g, 0.215mmol) was added and H₂ was bubbled in for a few minutes. The reactionwas stirred under H₂ balloon overnight. The reaction mixture wasfiltered through Celite and was washed with MeOH and concentrated togive pure compound 40 (1 g, 100% yield). ¹H NMR (400 MHz, DMSO-d6): δ7.41-7.30 (m, 2H), 7.27-7.21 (m, 1H), 7.06 (s, 2H), 4.65 (s, 4H), 3.23(s, 3H), 3.12 (s, 2H), 0.82 (s, 18H), 0.00 (s, 12H).

Step 5:

Amine compound 40 (1.0 g, 1.988 mmol) and Z-Gly-Gly-Gly-OH (662 mg,2.385 mmol) were dissolved in DMF (6.63 mL). EDC.HCl (457 mg, 2.385mmol) and HOBT (304 mg, 1.988 mmol) were added to the reaction mixture,followed by DIEA (694 μL, 3.98 mmol). The reaction was stirred at rtovernight. The reaction mixture was diluted with EtOAc and was washedwith sat'd NaHCO₃, brine and water (2×). The organic layer was driedover Na₂SO₄, filtered and concentrated. The crude residue was purifiedby silica gel flash chromatography (MeOH/DCM, gradient, 0% to 10%) toobtain compound 41 as a white sticky foam (994 mg, 71% yield). ¹H NMR(400 MHz, CDCl₃): δ 7.38-7.32 (m, 7H), 7.31-7.27 (m, 2H), 7.01 (s, 2H),5.13 (s, 2H), 4.74 (s, 4H), 3.97 (d, 2H, J=4.6 Hz), 3.92 (d, 2H, J=5.3Hz), 3.74 (d, 2H, J=3.7 Hz), 3.27 (s, 3H), 0.94 (s, 18H), 0.11 (s, 12H).

Step 6:

Compound 41 (994 mg, 1.418 mmol) was suspended in MeOH (6.65 mL) andwater (443 μL) and was purged with N₂. Pd/C (10% wet, 302 mg, 0.284mmol) was added and H₂ was bubbled in for a few minutes. The reactionwas stirred under H₂ balloon overnight. The solution was filteredthrough Celite and was washed with MeOH and concentrated to obtain purecompound 42 (725 mg, 90% yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.10-7.97(m, 1H), 7.91-7.85 (m, 1H), 7.31-7.23 (m, 1H), 7.05 (s, 2H), 7.65 (s,4H), 3.68-3.62 (m, 2H), 3.56-3.45 (m, 1H), 3.09 (s, 3H), 3.08-3.06 (m,2H), 3.06-3.03 (m, 2H), 0.82 (s, 18H), 0.00 (s, 12H). LCMS=5.574 min (8min method). Mass observed (ESI⁺): 567.30 (M+H).

Step 7:

Amine compound 42 (725 mg, 1.279 mmol) and mono methyladipate (246 mg,1.535 mmol) were dissolved in DMF (6.5 mL). EDC.HCl (294 mg, 1.535 mmol)and HOBt (196 mg, 1.279 mmol) were added to the reaction mixture,followed by DIEA (447 μL, 2.56 mmol). The reaction was stirred at rtovernight. The reaction mixture was diluted with DCM (20 mL) and waswashed with sat'd NH₄Cl, sat'd NaHCO₃, water and brine. The organiclayer was dried over Na₂SO₄, filtered and concentrated. The crudeproduct was purified by silica gel flash chromatography (MeOH/DCM,gradient, 0% to 10%) to obtain compound 43 (425 mg, 33% yield). ¹H NMR(400 MHz, CDCl₃): δ 7.30 (s, 1H), 7.01 (s, 2H), 6.89-6.85 (m, 1H),6.75-6.72 (m, 1H), 6.41-6.40 (m, 1H), 4.73 (s, 4H), 3.98-3.96 (m, 4H),3.74 (bd, 2H, J=3.5 Hz), 3.66 (s, 3H), 3.27 (s, 3H), 2.33 (t, 2H, J=6.8Hz), 2.28 (t, 2H, J=6.5 Hz), 0.94 (s, 18H), 0.11 (s, 12H). LCMS=7.709min (8 min method). Mass observed (ESI⁺): 709.35 (M+H).

Step 8:

Compound 43 (422 mg, 0.417 mmol) was dissolved in THF (1.89 mL) andwater (189 μL). HCl (aqueous, 5 M) (833 μL, 4.17 mmol) was added and thereaction was stirred at rt for 2.5 h. The reaction mixture wasconcentrated. ACN (˜15 mL) was added to the residue and wasconcentrated. This was repeated two more times to obtain compound 44 asa white foam (200 mg, 100% yield). LCMS=0.389 min (8 min method). ¹H NMR(400 MHz, DMSO-d6): δ 8.09-8.04 (m, 2H), 7.93-7.90 (m, 1H), 7.30 (bs,1H), 7.14 (s, 2H), 4.52 (s, 4H), 3.71-3.68 (m, 4H), 3.58 (s, 3H), 3.17(bs, 3H), 2.22-2.18 (m, 2H), 2.15-2.12 (m, 2H), 1.53-1.47 (m, 4H).

Step 9:

Diol compound 44 (110 mg, 0.229 mmol) and CBr₄ (228 mg, 0.687 mmol) weredissolved in DMF (2.29 mL). PPh₃ (180 mg, 0.687 mmol) was added to thereaction mixture, at which point the reaction turned red-pink with aslight exotherm. The reaction was stirred under Ar for 6 h. The reactionmixture was diluted with CH₂Cl₂/MeOH (10:1) and was washed with waterand brine. The organic layer was dried over Na₂SO₄ and concentrated. Thecrude residue was purified by silica gel flash chromatography(MeOH/CH₂Cl₂, gradient, 0% to 10%) to obtain compound 45 (30 mg, 22%yield). ¹H NMR (400 MHz, CDCl₃): δ 7.46 (bs, 1H), 7.32-7.26 (m, 2H),7.26-7.19 (m, 2H), 6.89-6.85 (m, 1H), 4.60 (d, 2H, J=3.6 Hz), 4.48 (d,2H, J=3.9 Hz), 3.98 (d, 4H, J=5.1 Hz), 3.76 (bs, 1H), 3.67 (s, 3H), 3.30(bs, 3H), 2.34 (bt, 2H, J=6.7 Hz), 2.30 (bt, 2H, J=6.6 Hz), 1.70-1.64(m, 4H). LCMS=4.326 min (8 min method). Mass observed (ESI⁺): 605.10(M+H).

Step 10:

Compound 46 was prepared similarly as compound 11 in Example 1. Compound46 was obtained as a yellow solid after purification (40 mg, 59% yield).LCMS=4.751 min (8 min method). Mass observed (ESI⁺): 1033.35 (M+H).

Step 11:

Compound 47 was prepared similarly as compound 12 in Example 1. Compound47 was obtained as a white solid after C18 purification (14 mg, 32%yield). LCMS=5.857 min (15 min method). Mass observed (ESI⁺): 1035.7(M+H).

Step 12:

Compound 48 was prepared similarly as 22 in Example 2. Compound 48 wasobtained as a yellow solid after silica plug (7 mg, 100% yield).LCMS=4.817 min (8 min method). Mass observed (ESI⁺): 1021.35 (M+H).

Step 13:

Compound 49 was prepared similarly as compound 14 in Example 1.2,5-dioxopyrrolidin-1-yl2-(3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)-3,6,9,12-tetraoxo-2,5,8,11-tetraazaheptadecan-17-oate,compound 49 was obtained as a white solid after C18 purification (6.5mg, 74% yield). LCMS=5.805 min (15 min method). Mass observed (ESI⁺):1118.7 (M+H).

Example 5. Synthesis of 2,5-dioxopyrrolidin-1-yl6-(((S)-1-(((R)-1-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((R)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-1-oxopropan-2-yl)amino)-1-oxopropan-2-yl)amino)-6-oxohexanoate(Compound 80)

Step 1:

(S)-2-(((benzyloxy)carbonyl)amino)propanoic acid (5 g, 22.40 mmol) and(R)-tert-butyl 2-aminopropanoate hydrochloride (4.48 g, 24.64 mmol) weredissolved in anhydrous DMF (44.8 ml). EDC.HCl (4.72 g, 24.64 mmol), HOBt(3.43 g, 22.40 mmol), and then DIPEA (9.75 ml, 56.0 mmol) were added.The reaction was stirred under argon at room temperature, overnight. Thereaction mixture was diluted with dichloromethane and then washed withsaturated ammonium chloride, saturated sodium bicarbonate, water, andbrine. The organic layer was dried over sodium sulfate and concentrated.The crude oil was purified via silica gel chromatography (Hexanes/EthylAcetate) to yield compound 71 (5.6 g, 71% yield). ¹H NMR (400 MHz,CDCl₃): δ 7.39-7.34 (m, 5H), 6.54 (s, 1H) 5.28 (s, 1H), 5.15 (s, 2H),4.47-4.43 (m, 1H), 4.48 (s, 1H), 1.49 (s, 9H), 1.42-1.37 (m, 6H).

Step 2:

Compound 71 (5.6 g, 15.98 mmol) was dissolved in methanol (50.7 mL) andwater (2.54 mL). The solution was purged with argon for five minutes.Palladium on carbon (wet, 10%) (0.850 g, 0.799 mmol) was added slowly.The reaction was stirred overnight under an atmosphere of hydrogen. Thesolution was filtered through Celite, rinsed with methanol andconcentrated. The residue was azeotroped with methanol and acetonitrileand the resulting oil was placed directly on the high vacuum to givecompound 72 (3.57 g, 100% yield) which was used directly in the nextstep. ¹H NMR (400 MHz, CDCl₃): δ 7.67 (s, 1H), 4.49-4.42 (m, 1H),3.54-3.49 (m, 1H), 1.48 (s, 9H), 1.40 (d, 3H, J=7.2 Hz), 1.36 (d, 3H,J=6.8 Hz).

Step 3:

Compound 72 (3.57 g, 16.51 mmol) and mono methyladipate (2.69 mL, 18.16mmol) were dissolved in anhydrous DMF (55.0 mL). EDC.HCl (3.48 g, 18.16mmol) and HOBt ((2.53 g, 16.51 mmol) were added, followed by DIPEA (5.77mL, 33.0 mmol). The mixture was stirred overnight at room temperature.The reaction was diluted with dichloromethane/methanol (80 mL, 5:1) andwashed with saturated ammonium chloride, saturated sodium bicarbonate,and brine. It was dried over sodium sulfate, filtered and stripped. Thecompound was azeotroped with acetonitrile (5×), then pumped on the highvacuum at 35° C. to give compound 73 (5.91 g, 100% yield). The crudematerial was taken onto next step without purification. ¹H NMR (400 MHz,CDCl₃): δ 6.67 (d, 1H, J=6.8 Hz), 6.22 (d, 1H, J=7.2 Hz), 4.56-4.49 (m,1H), 4.46-4.38 (m, 1H), 3.68 (s, 3H), 2.37-2.33 (m, 2H), 2.27-2.24 (m,2H), 1.70-1.68 (m, 4H), 1.47 (s, 9H), 1.40 (s, 3H), 1.38 (s, 3H).

Step 4:

Compound 73 (5.91 g, 16.5 mmol) was stirred in TFA (25.4 mL, 330 mmol)and deionized water (1.3 mL) at room temperature for three hours. Thereaction mixture was concentrated with acetonitrile and placed on highvacuum to dryness to give crude compound 74 (4.99 g, 100% yield). ¹H NMR(400 MHz, CDCl₃): δ 7.44 (d, 1H, J=7.2 Hz), 6.97 (d, 1H, J=8.0 Hz),4.81-4.73 (m, 1H), 4.59-4.51 (m, 1H), 3.69 (s, 3H), 2.39-2.32 (m, 2H),2.31-2.23 (m, 2H), 1.70-1.61 (m, 4H), 1.48 (d, 3H, J=7.2 Hz), 1.40 (d,3H, J=7.2 Hz).

Step 5:

Compound 74 (4.8 g, 15.88 mmol) was dissolved in anhydrousdichloromethane (101 mL) and anhydrous methanol (50.4 mL).(5-amino-1,3-phenylene)dimethanol (2.316 g, 15.12 mmol) and EEDQ (7.48g, 30.2 mmol) were added and the reaction was stirred at roomtemperature, overnight. The solvent was stripped and the crude materialpurified by silica gel chromatography (dichloromethane/methanol) to givecompound 75 (1.65 g, 25% yield). ¹H NMR (400 MHz, DMSO-d6): δ 9.68 (s,1H), 8.29 (d, 1H, J=7.2 Hz), 8.11 (d, 1H, J=6.4 Hz), 7.52 (s, 2H), 6.97(s, 1H), 5.15 (s, 2H), 4.45 (s, 4H), 4.39-4.32 (m, 1H), 4.28-4.21 (m,1H), 3.57 (s, 3H), 2.30-2.27 (m, 2H), 2.17-2.13 (m, 2H), 1.54-1.45 (m,4H) 1.30 (d, 3H, J=7.2 Hz), 1.20 (d, 3H, J=7.2 Hz). MS (m/z): 460.2(M+Na)⁺.

Step 6:

Compound 75 (0.486 g, 1.111 mmol) and carbon tetrabromide (1.105 g, 3.33mmol) were dissolved in anhydrous DMF (11.11 mL). Triphenylphosphine(0.874 g, 3.33 mmol) was added and the reaction stirred under argon forfour hours. The reaction mixture was diluted with DCM/MeOH (10:1) andwashed with water and brine. It was dried over sodium sulfate, filtered,and concentrated. The crude material was purified by silica gelchromatography (DCM/MeOH) to give compound 76 (250 mg, 40% yield). ¹HNMR (400 MHz, DMSO-d6): δ 9.82 (s, 1H), 8.38 (d, 1H, J=7.2 Hz), 8.17 (d,1H, J=6.0 Hz), 7.76 (s, 2H), 7.22 (s, 1H), 4.66 (s, 4H), 4.38-4.31 (m,1H), 4.25-4.19 (m, 1H), 3.56 (s, 3H), 2.30-2.27 (m, 2H), 2.18-2.15 (m,2H), 1.53-1.51 (m, 4H), 1.32 (d, 3H, J=7.2 Hz), 1.21 (d, 3H, J=6.8 Hz).

Step 7:

Compound 77 was prepared similarly as 11 in Example 1. The crudematerial was purified by silica gel chromatography(dichloromethane/methanol) to give compound 77 (340 mg, 60% yield, 77%purity). LCMS=5.87 min (15 min method). MS (m/z): 990.6 (M+1)⁺.

Step 8:

Compound 78 was prepared similarly as compound 12 in Example 1 The crudematerial was purified via RPHPLC (C18 column, Acetonitrile/Water) togive compound 78 (103 mg, 30% yield). LCMS=6.65 min (15 min method). MS(m/z): 992.7 (M+1)⁺.

Step 9:

Compound 78 was prepared similarly as 22 in Example 2. The crudematerial was passed through a silica plug to give compound 79 (38 mg,55% yield, 75% purity). LCMS=5.83 min (15 min method). MS (m/z): 978.6(M+1)⁺.

Step 10:

Compound 80 was prepared similarly as compound 14 in Example 1. Thecrude material was purified via RPHPLC (C18 column, Acetonitrile/Water)to give 2,5-dioxopyrrolidin-1-yl6-(((S)-1-(((R)-1-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((R)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-1-oxopropan-2-yl)amino)-1-oxopropan-2-yl)amino)-6-oxohexanoate,compound 80 (6.5 mg, 30% yield). LCMS=6.53 min (15 min method). MS(m/z): 1075.7 (M+1)⁺ and 1097.7 (M+Na)⁺.

Example 6. Synthesis of 2,5-dioxopyrrolidin-1-yl6-(((S)-1-(((S)-1-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((R)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-1-oxopropan-2-yl)amino)-1-oxopropan-2-yl)amino)-6-oxohexanoate,Compound 90

Step 1:

(S)-2-(((benzyloxy)carbonyl)amino)propanoic acid (5 g, 22.40 mmol) and(S)-tert-butyl 2-aminopropanoate hydrochloride (4.48 g, 24.64 mmol) weredissolved in anhydrous DMF (44.8 mL). EDC.HCl (4.72 g, 24.64 mmol), HOBt(3.43 g, 22.40 mmol), and DIPEA (9.75 mL, 56.0 mmol) were added. Thereaction stirred under argon, at room temperature, overnight. Thereaction mixture was diluted with dichloromethane and then washed withsaturated ammonium chloride, saturated sodium bicarbonate, water, andbrine. The organic layer was dried over sodium sulfate and concentrated.The crude oil was purified via silica gel chromatography (Hexanes/EthylAcetate) to yield compound 81 (6.7 g, 85% yield). ¹H NMR (400 MHz,CDCl₃): δ 7.38-7.31 (m, 5H), 6.53-6.42 (m, 1H), 5.42-5.33 (m, 1H), 5.14(s, 2H), 4.48-4.41 (m, 1H), 4.32-4.20 (m, 1H), 1.49 (s, 9H), 1.42 (d,3H, J=6.8 Hz), 1.38 (d, 3H, J=7.2 Hz).

Step 2:

Compound 81 (6.7 g, 19.12 mmol) was dissolved in methanol (60.7 mL) andwater (3.03 mL). The solution was purged with argon for five minutes.Palladium on carbon (wet, 10%) (1.017 g, 0.956 mmol) was added slowly.The reaction was stirred overnight under an atmosphere of hydrogen. Thesolution was filtered through Celite, rinsed with methanol andconcentrated. It was azeotroped with methanol and acetonitrile and theresulting oil was placed directly on the high vacuum to give compound 82(4.02 g, 97% yield) which was used directly in the next step. ¹H NMR(400 MHz, CDCl₃): δ 7.78-7.63 (m, 1H), 4.49-4.42 (m, 1H), 3.55-3.50 (m,1H), 1.73 (s, 2H), 1.48 (s, 9H), 1.39 (d, 3H, J=7.2 Hz), 1.36 (d, 3H,J=6.8 Hz).

Step 3:

Compound 82 (4.02 g, 18.59 mmol) and mono methyladipate (3.03 mL, 20.45mmol) were dissolved in anhydrous DMF (62.0 mL). EDC.HCl (3.92 g, 20.45mmol), HOBt (2.85 g, 18.59 mmol) and DIPEA (6.49 mL, 37.2 mmol) wereadded. The mixture was stirred overnight at room temperature. Thereaction was diluted with dichloromethane/methanol (150 mL, 5:1) andwashed with saturated ammonium chloride, saturated sodium bicarbonate,and brine. It was dried over sodium sulfate, filtered and stripped. Thecompound was azeotroped with acetonitrile (5×), then pumped on the highvacuum at 35° C. to give compound 83 (6.66 g, 100% yield). The crudematerial was taken onto next step without purification. ¹H NMR (400 MHz,CDCl₃): δ 6.75 (d, 1H, J=6.8 Hz), 6.44 (d, 1H, J=6.8 Hz), 4.52-4.44 (m,1H), 4.43-4.36 (m, 1H), 3.65 (s, 3H), 2.35-2.29 (m, 2H), 2.25-2.18 (m,2H), 1.71-1.60 (m, 4H), 1.45 (s, 9H), 1.36 (t, 6H, J=6.0 Hz).

Step 4:

Compound 83 (5.91 g, 16.5 mmol) was stirred in TFA (28.6 mL, 372 mmol)and deionized water (1.5 mL) at room temperature for three hours. Thereaction mixture was concentrated with acetonitrile and placed on highvacuum to give crude compound 84 as a sticky solid (5.88 g, 100% yield).¹H NMR (400 MHz, CDCl₃): δ 7.21 (d, 1H, J=6.8 Hz), 6.81 (d, 1H, J=7.6Hz), 4.69-4.60 (m, 1H), 4.59-4.51 (m, 1H), 3.69 (s, 3H), 2.40-2.33 (m,2H), 2.31-2.24 (m, 2H), 1.72-1.63 (m, 4H), 1.51-1.45 (m, 3H), 1.42-1.37(m, 3H).

Step 5:

Compound 84 (5.6 g, 18.52 mmol) was dissolved in anhydrousdichloromethane (118 mL) and anhydrous methanol (58.8 mL).(5-amino-1,3-phenylene)dimethanol (2.70 g, 17.64 mmol) and EEDQ (8.72 g,35.3 mmol) were added and the reaction was stirred at room temperature,overnight. The solvent was stripped and ethyl acetate was added. Theresulting slurry was filtered, washed with ethyl acetate and dried undervacuum/N₂ to give compound 85 (2.79 g, 36% yield). ¹H NMR (400 MHz,DMSO-d6): δ 9.82 (s, 1H), 8.05, (d, 1H, J=9.2 Hz), 8.01 (d, 1H, J=7.2Hz), 7.46 (s, 2H), 6.95 (3, 1H), 5.21-5.12 (m, 2H), 4.47-4.42 (m, 4H),4.40-4.33 (m, 1H), 4.33-4.24 (m, 1H), 3.58 (s, 3H), 2.33-2.26 (m, 2H),2.16-2.09 (m, 2H), 1.54-1.46 (m, 4H), 1.30 (d, 3H, J=7.2 Hz), 1.22 (d,3H, J=4.4 Hz).

Step 6:

Compound 85 (0.52 g, 1.189 mmol) and carbon tetrabromide (1.183 g, 3.57mmol) were dissolved in anhydrous DMF (11.89 mL). Triphenylphosphine(0.935 g, 3.57 mmol) was added and the reaction stirred under argon forfour hours. The reaction mixture was diluted with DCM/MeOH (10:1) andwashed with water and brine, dried over sodium sulfate, filtered, andconcentrated. The crude material was purified by silica gelchromatography (DCM/MeOH) to give compound 86 (262 mg, 39% yield). ¹HNMR (400 MHz, DMSO-d6): δ 10.01 (s, 1H), 8.11 (d, 1H, J=6.8 Hz), 8.03(d, 1H, J=6.8 Hz), 7.67 (s, 2H), 7.21 (s, 1H), 4.70-4.64 (m, 4H),4.40-4.32 (m, 1H), 4.31-4.23 (m, 1H), 3.58 (s, 3H), 2.34-2.26 (m, 2H),2.18-2.10 (m, 2H), 1.55-1.45 (m, 4H), 1.31 (d, 3H, J=7.2 Hz), 1.21 (d,3H, J=7.2 Hz).

Step 7:

Compound 87 was prepared similarly as compound 11 in Example 1. Thecrude material was purified by silica gel chromatography(dichloromethane/methanol) to give compound 87 (336 mg, 74% yield).LCMS=5.91 min (15 min method). MS (m/z): 990.6 (M+1)⁺.

Step 8:

Compound 88 was prepared similarly as compound 12 in Example 1. Thecrude material was purified via RPHPLC (C18 column, Acetonitrile/Water)to give compound 88 (85.5 mg, 25% yield). LCMS=6.64 min (15 min method).MS (m/z): 992.6 (M+1)⁺.

Step 9:

Compound 88 was prepared similarly as 22 in Example 2. The crudematerial was passed through a silica plug to give compound 89 (48.8 mg,80% yield). LCMS=5.89 min (15 min method). MS (m/z): 978.6 (M+1)⁺.

Step 10:

Compound 90 was prepared similarly as 14 in Example 1. The crudematerial was purified via RPHPLC (C18 column, Acetonitrile/Water) togive 2,5-dioxopyrrolidin-1-yl6-(((S)-1-(((S)-1-((3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((R)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-1-oxopropan-2-yl)amino)-1-oxopropan-2-yl)amino)-6-oxohexanoate,compound 90 (8.2 mg, 30% yield). LCMS=6.64 min (15 min method). MS(m/z): 1075.4 (M+1)⁺.

Example 7. Synthesis of 2,5-dioxopyrrolidin-1-yl1-(3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)-1,4,7,10-tetraoxo-2,5,8,11-tetraazatetradecan-14-oate(Compound 63)

Step 1:

Z-Gly-Gly-GlyOH compound 50 (1.0 g, 3.09 mmol) and 1-alaninemethylester.HCl (453 mg, 3.25 mmol) were dissolved in DMF (12.37 mL).EDC.HCl (623 mg, 3.25 mmol) and HOBt (497 mg, 3.25 mmol) were added tothe reaction mixture, followed by DIEA (1.08 mL, 6.19 mmol). Thereaction was stirred at rt overnight. The next day, a lot of whiteprecipitate had formed. The reaction mixture was diluted withCH₂Cl₂/MeOH (5:1, 30 mL) and was washed with sat'd NaHCO₃, sat'd NH₄Cland brine. The organic layer became clowdy. Added EtOAc (15 mL) to theorganic layer to precipitate out the product. The mixture was filteredand the solid was washed water (10 mL) and CH₃CN (2×15 mL) to obtainpure compound 51 as a white powder (880 mg, 70% yield) withoutpurification. ¹H NMR (400 MHz, DMSO-d6): δ 8.16 (bt, 1H, J=5.4 Hz), 8.11(bt, 1H, J=5.6 Hz), 7.88-7.85 (m, 1H), 7.49 (bt, 1H, J=5.5 Hz),7.40-7.31 (m, 5H), 5.04 (s, 2H), 3.74 (d, 2H, J=5.5 Hz), 3.67 (t, 4H,J=6.2 Hz), 3.60 (s, 3H), 3.29 (q, 1H, J=6.4 Hz), 2.47 (t, 3H, J=6.9 Hz).

Step 2:

Compound 51 (876 mg, 2.145 mmol) was dissolved in MeOH (20.4 mL) andwater (1.02 mL) and was purged with Ar. The solution was degassed for 5min. Pd/C (10%, wet with 50% water, 228 mg) was added slowly. H₂ wasbubbled into the through a balloon for a minute. The reaction wasstirred under a H₂ balloon overnight. H₂O (˜3 mL) was added to reactionmixture to dissolve all white solids formed. The solution was thenfiltered through Celite and the filter cake was washed with MeOH (30 mL)and concentrated. The residue was dissolved in CH₃CN (20 mL) and wasconcentrated. This was repeated 2 more times. The resulting gummy solidwas precipitated out with the addition of CH₃CN (˜15 mL). The thickwhite slurry was stirred for 10 min, filtered and washed with CH₃CN. Thesolid was dried under vacuum/N₂ for 1.5 h to obtain compound 52 as awhite solid (450 mg, 76% yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.18-8.12(m, 2H), 7.88 (t, 1H, J=5.4 Hz), 3.75 (s, 2H), 3.65 (d, 2H, J=5.9 Hz),3.6 (s, 3H), 3.33-3.27 (m, 4H), 2.47 (t, 2H, J=7.0 Hz), 1.94 (bs, 1H).

Step 3:

NaOH (1.665 g, 41.6 mmol) was added to a stirred solution of trimethylbenzene-1,3,5-tricarboxylate compound 53 (5 g, 19.82 mmol) in MeOH (66.1mL) and water (13.22 mL). The reaction mixture was refluxed under Ar for3 h. Lots of white precipitate had formed. The solution was cooled to rtand was diluted with H₂O until all solids were dissolved. The mixturewas acidified to pH˜2-3 with aqueous 5 N HCl, extracted with EtOAc (3×),dried over Na₂SO₄, filtered and concentrated. The crude product wasdissolved in hot EtOAc (50 mL) and was cooled to rt slowly. Theprecipitate was filtered (precipitate was by-product and not product).The mother liquor was concentrated to obtain compound 54 as a whitesolid (3.45 g, 78% yield). ¹H NMR (400 MHz, DMSO-d6): δ 13.62 (bs, 2H),8.65 (s, 3H), 3.93 (s, 3H). LCMS=3.209 min (8 min method). Mass observed(ESI⁺): 244.90 (M+H).

Step 4:

Diacid compound 54 (1.0 g, 4.46 mmol) was dissolved in THF (17.84 mL).The solution was cooled to 0° C. and BH₃.DMS (2 M in THF) (8.92 mL,17.84 mmol) was added slowly under Ar. The reaction was stirred at 0° C.for 5 min, then was warmed to rt and stirred overnight. The reaction wasopened to air and was slowly quenched with MeOH, followed by slowaddition of H₂O until no gas evolution was observed. The mixture wasextracted with EtOAc (2×) and the layers were separated. The organiclayers were washed with aqueous ˜3% H₂O₂, aq. citric acid solution andbrine, dried over Na₂SO₄, filtered and concentrated. The crude residuewas purified by silica gel flash chromatography (EtOAc/hexanes,gradient, 20% to 100%) to obtain diol compound 55 as a white solid (385mg, 44% yield). ¹H NMR (400 MHz, DMSO-d6): δ 7.81 (s, 2H), 7.52 (s, 1H),5.33 (bs, 2H), 4.56 (s, 4H), 3.86 (s, 3H).

Step 5:

Diol compound 55 (320 mg, 1.631 mmol) was dissolved in DCM (10.9 mL)under Ar. The solution was cooled to −5° C. and TEA (0.568 mL, 4.08mmol) was added, followed by a slow addition of MsCl (0.292 mL, 3.75mmol), at which point the color immediately turned yellow upon addition,then dark red/brown. The reaction mixture was stirred at −5° C. under Arfor 1.5 h The reaction mixture was quenched with ice water and wasextracted with EtOAc (2×). The organic layer was washed with water (2×),dried over Na₂SO₄, filtered and concentrated to obtain the crudedimesylate compound 56 (435 mg, 76% yield).

Step 6:

Dimesylate compound 56 (435 mg, 1.11 mmol) was dissolved in DMF (5.55mL). IGN monomer compound 10 (719 mg, 2.444 mmol) was added, followed byand K₂CO₃ (384 mg, 2.78 mmol) and was stirred at rt under Ar overnight.Water (20 mL) was added to precipitate out the product. The slurry wasstirred for 5 min, filtered and dried under vacuum/N₂ for 1.5 h. Thecrude residue was purified by silica gel flash chromatography(EtOAc/hexanes, gradient, 50% to 100%; then 5% MeOH/DCM) to obtaincompound 57 as a yellow solid (535 mg, 64% yield, 2 steps). LCMS=6.973min (15 min method). Mass observed (ESI⁺): 749.4 (M+H).

Step 7:

compound 57 (100 mg, 0.134 mmol) was dissolved in DCE (1.34 mL).Trimethylstannanol (362 mg, 2.003 mmol) was added and was heated at 80°C. overnight. The reaction mixture was cooled to rt and was diluted withwater. The aqueous layer was acidified to pH˜4 with 1 M HCl and wasextracted with DCM (3×), dried over Na₂SO₄, filtered and concentrated.Crude product was plugged through a short silica plug and was flushedwith DCM/MeOH (10:1, 50 mL) and concentrated to obtain compound 58 as apale yellow solid (100 mg, 100% yield). LCMS=5.872 min (15 min method).Mass observed (ESI⁺): 735.3 (M+H).

Step 8:

Acid compound 58 (80 mg, 0.087 mmol) and amine compound 52 (36 mg, 0.131mmol) were dissolved in DMF (871 μL). EDC.HCl (25 mg, 0.131 mmol) andDMAP (10.6 mg, 0.087 mmol) were added and was stirred at rt for 4 h.Water (4 mL) was added to precipitate out the product. The slurry wasstirred for 5 min, filtered and was dried under vacuum/N₂. The cruderesidue was purified by silica gel flash chromatography (MeOH/DCM,gradient, 0% to 20%) to obtain compound 60 as a yellow solid (37 mg, 43%yield). LCMS=4.605 min (8 min method). Mass observed (ESI⁺): 991.35(M+H).

Step 9:

Compound 61 was prepared similarly as compound 12 in Example 1. Compound61 was obtained as a white solid after C18 purification (8 mg, 25%yield). LCMS=5.421 min (15 min method). Mass observed (ESI⁺): 993.7(M+H).

Step 10:

Compound 62 was prepared similarly as compound 22 in Example 2. Crudecompound 62 was obtained as a yellow solid after plugging through ashort silica plug (13 g, 90% yield). LCMS=4.693 min (8 in method). Massobserved (ESI⁺): 979.35 (M+H).

Step 11:

Compound 63 was prepared similarly as compound 14 in Example 1.2,5-dioxopyrrolidin-1-yl1-(3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)-1,4,7,10-tetraoxo-2,5,8,11-tetraazatetradecan-14-oate,compound 63 was obtained as a white solid after C18 purification (4 mg,31% yield). LCMS=5.495 min (15 min method). Mass observed (ESI⁺): 1076.7(M+H).

Example 8. Synthesis of 2,5-dioxopyrrolidin-1-yl3-((S)-2-((S)-2-(3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)benzamido)propanamido)propanamido)propanoate (Compound 70)

Step 1:

Z-L-Ala-L-Ala-OH compound 64 (3.0 g, 10.19 mmol) and β-alaninemethylester.HCl (1.565 g, 11.21 mmol) were dissolved in DMF (20.39 mL).EDC.HCl (2.150 g, 11.21 mmol) and HOBt (1.561 g, 10.19 mmol) were added,followed by DIPEA (4.44 mL, 25.5 mmol). The reaction was stirred rtunder Ar overnight. The reaction mixture was diluted with EtOAc and waswashed with sat'd NH₄Cl, sat'd NaHCO₃ and brine. Hexanes was added tothe organic layer, at which point the solution became clowdy withprecipitate. The slurry was stirred for a few minutes, filtered andwashed solids with EtOAc/hexanes (3:1). The solid was dried undervacuum/N₂ to obtain pure compound 65 as a white solid (3.11 g, 80%yield). ¹H NMR (400 MHz, DMSO-d6): δ 7.91 (d, 2H, J=7.0 Hz), 7.46 (d,1H, J=7.4 Hz), 6.39-7.30 (m, 5H), 5.02 (d, 2H, J=2.3 Hz), 4.20 (p, 1H,J=7.2 Hz), 4.04 (p, 1H, J=7.3 Hz), 3.59 (s, 3H), 3.30-3.22 (m, 1H), 2.45(t, 2H, J=6.8 Hz), 1.18 (apparent t, 6H, J=7.2 Hz). LCMS=3.942 min (8min method). Mass observed (ESI⁺): 380.10 (M+H).

Step 2:

Compound 65 (1.0 g, 2.64 mmol) was dissolved in methanol (12.55 mL),water (0.628 mL) and THF (2 mL). The solution was purged with Ar andthen was degassed for 5 min. Pd/C (10%, wet with 50% water, 0.140 g) wasadded slowly. H₂ was bubbled into the solution for a minute and thereaction was further stirred under a H₂ balloon (1 atm) overnight. Thereaction mixture was filtered through Celite and was washed with MeOH(30 mL) and concentrated. CH₃CN (15 mL) was added to the residue and wasconcentrated. This was repeated 2 more times to obtain compound 66 as anoff white solid (650 mg, 100% yield). ¹H NMR (400 MHz, DMSO-d6): δ8.03-7.99 (m, 2H), 4.24-4.18 (m, 1H), 3.60 (s, 3H), 3.31-3.22 (m, 5H),2.46 (t, 2H, J=6.8 Hz), 1.17 (d, 3H, J=7.0 Hz), 1.12 (d, 3H, J=6.9 Hz).

Step 3:

Compound 67 was prepared similarly as 60 in Example 7. Compound 67 wasobtained as a yellow solid after silica gel flash chromatography (69 mg,53% yield). LCMS=4.843 min (8 min method). Mass observed (ESI⁺): 962.25(M+H).

Step 4:

Compound 68 was prepared similarly as compound 12 in Example 1. Compound68 was obtained as a white solid after C18 purification (11.5 mg, 19%yield). LCMS=5.136 min (8 min method). Mass observed (ESI⁺): 964.35(M+H).

Step 5:

Compound 69 was prepared similarly as compound 22 in Example 2. Crudecompound 69 was obtained as a yellow solid after plugging through ashort silica plug (13 mg, 100% yield). LCMS=5.640 min (15 min method).Mass observed (ESI⁺): 950.4 (M+H).

Step 6:

Compound 70 was prepared similarly as compound 14 in Example 1.2,5-dioxopyrrolidin-1-yl-3-((S)-2-((S)-2-(3-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)-5-((((S)-8-methoxy-6-oxo-12a,13-dihydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)benzamido)propanamido)propanamido) propanoate, compound 70 was obtained as a whitesolid after C18 purification (5 mg, 35% yield). LCMS=6.138 min (15 minmethod). Mass observed (ESI⁺): 1047.4 (M+H).

Example 9. Synthesis of(12S,12aS)-9-((3-(2-(2-(2-(4-mercapto-4-methylpentanamido)acetamido)acetamido)acetamido)-5-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)benzyl)oxy)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indole-12-sulfonicacid (Compound 98)

Step 1:

Compound 4 (2.0 g, 8.15 mmol) and 4-methyl-4-(methyldisulfanyl)pentanoicacid (1.743 g, 8.97 mmol) were dissolved in anhydrous DMF (27.2 mL).EDC.HCl (1.719 g, 8.97 mmol) and HOBt (1.249 g, 8.15 mmol) were added,followed by DIPEA (2.85 mL, 16.31 mmol). The mixture was stirred at roomtemperature overnight. The reaction was diluted withdichloromethane/methanol (5:1) and washed with saturated ammoniumchloride, saturated sodium bicarbonate, and brine. It was dried oversodium sulfate, filtered and stripped. The crude oil was azeotroped withacetonitrile (3×), then pumped on high vac at 35° C. for about 1.5 hoursto give compound 91, which was taken on without further purification(3.44 g, 100% yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.18-8.09 (m, 3H),3.76-3.68 (m, 6H), 2.41 (s, 3H), 2.28-2.21 (m, 2H), 1.84-1.77 (m, 2H),1.41 (s, 9H), 1.25 (s, 6H).

Step 2:

Compound 91 (3.44 g, 8.15 mmol) was stirred in TFA (12.56 mL, 163 mmol)and deionized water (0.65 mL) at room temperature for 3.5 hours. Thereaction was diluted with acetonitrile and evaporated to dryness. Thecrude solid was slurried with ethyl acetate, filtered and rinsed withethyl acetate and then dichloromethane/methanol (1:1) to give compound92 (2.98 g, 100% yield). ¹H NMR (400 MHz, DMSO-d6): δ 8.19-8.08 (m, 3H),3.80-3.68 (m, 6H), 2.41 (s, 3H), 2.28-2.20 (m, 2H), 1.85-1.76 (m, 2H),1.25 (s, 6H).

Step 3:

Compound 92 (1.74 g, 4.76 mmol) was dissolved in dichloromethane (30.2mL) and methanol (15.11 mL).N-Ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (2.243 g, 9.07 mmol) and(5-amino-1,3-phenylene)dimethanol (0.695 g, 4.53 mmol) were added andthe reaction was stirred at room temperature overnight. The solvent wasremoved and ethyl acetate was added. The solid was filtered throughCelite and washed with ethyl acetate and then methanol. The filtrate wasevaporated and purified by silica gel chromatography(Dichloromethan/Methanol) to give compound 93 (569 mg, 25% yield). ¹HNMR (400 MHz, DMSO-d6): δ 9.74 (s, 1H), 8.24-8.15 (m, 3H), 7.45 (s, 2H),6.96 (s, 1H), 5.17 (t, 2H, J=5.6 Hz), 4.45 (d, 4H, J=5.6 Hz), 3.87 (d,2H, J=6.0 Hz), 3.77 (d, 2H, J=6.0 Hz), 3.73 (d, 2H, J=5.6 Hz), 2.40 (s,3H), 2.28-2.21 (m, 2H), 1.83-1.76 (m, 2H), 1.24 (s, 6H).

Step 4:

Compound 93 (305 mg, 0.609 mmol) was suspended in anhydrous DCM (5.992mL). Anhydrous DMF was added until the solution became homogeneous (˜2.5mL). The solution was cooled to −10° C. in an acetone/dry ice bath.Triethylamine (0.425 mL, 3.05 mmol) was added, followed bymethanesulfonic anhydride (274 mg, 1.523 mmol). The mixture stirred at−10° C. for 1 hour. The reaction was quenched with ice water andextracted with cold ethyl acetate/methanol (20:1). The organic layer waswashed with ice water and dried over anhydrous sodium sulfate, filteredand concentrated. The crude material was dried on high vacuum to givecompound 94 (380 mg, 95% yield). LCMS=4.2 min (15 min method). MS (m/z):655.0 (M−1)⁻.

Step 5:

Compound 95 was prepared similarly as compound 57 in Example 7. Thecrude solid was dissolved in Dichloromethane/Methanol (10:1) washed withwater and the organic dried over anhydrous sodium sulfate. The solventwas removed in vacuo and purified by silica gel chromatography(dichloromethane/methanol) to give compound 95 (445 mg, 42% yield, 54%purity). LCMS=6.64 min (15 min method). MS (m/z): 1053.4 (M+1)⁺ and1051.3 (M−1)⁻.

Step 6:

Compound 95 (445 mg, 0.423 mmol) was dissolved in 1,2-dichloroethane(2.82 mL). Sodium triacytoxyborohydride (80 mg, 0.359 mmol) was added atroom temperature and was stirred for 1 hour. The reaction was dilutedwith dichloromethane and washed with saturated ammonium chloride. Theorganic layer was washed with brine and dried to give of a mixture ofcompound 95, 96, and 96a (496 mg). This crude mixture was dissolved in2-Propanol (39.17 mL) and water (19.59 mL). Sodium bisulfite (245 mg,2.35 mmol) was added and was stirred at room temperature for 3.5 hours.The mixture was frozen and lyophilized to give a fluffy white solid thatwas purified by RPHPLC (C18, Acetonitrile/Water) to give compound 97 (54mg, 10% yield) and compound 96a (24 mg, 5% yield). LCMS (compound97)=4.83 min (15 min method) and LCMS (compound 96a)=8.05 min (15 minmethod).

Step 7:

To a stirred solution of compound 97 (54 mg, 0.047 mmol) in CH₃CN (3.85mL) was added freshly prepared TCEP/pH 6.5 buffer solution (TCEP.HCl(46.7 mg) was dissolved in a few drops of deionized water, followed bysaturated sodium bicarbonate dropwise until pH˜6.5. The solution wasdiluted with 0.55 mL of pH=6.5, 1 M sodium phosphate buffer) andmethanol (2.75 mL). The mixture was stirred at room temperature for 3hours and then frozen and lyophilized. The solid was purified by RPHPLC(C18, Acetonitrile/water) to give(12S,12aS)-9-((3-(2-(2-(2-(4-mercapto-4-methylpentanamido)acetamido)acetamido)acetamido)-5-((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)benzyl)oxy)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indole-12-sulfonicacid, compound 98 (2 mg, 4% yield). LCMS=4.32 min (15 min method). MS(m/z): 1089.3 (M−1)⁻.

Example 10. Synthesis ofN-(2-((2-((2-((3,5-bis((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-2-oxoethyl)amino)-2-oxoethyl)amino)-2-oxoethyl)-4-mercapto-4-methylpentanamide(Compound 99)

Compound 99 was prepared similarly as compound 98 in Example 9.N-(2-((2-((2-((3,5-bis((((S)-8-methoxy-6-oxo-11,12,12a,13-tetrahydro-6H-benzo[5,6][1,4]diazepino[1,2-a]indol-9-yl)oxy)methyl)phenyl)amino)-2-oxoethyl)amino)-2-oxoethyl)amino)-2-oxoethyl)-4-mercapto-4-methylpentanamide,compound 99 was obtained as a white solid after C18 purification (6.3mg, 27% yield). LCMS=7.26 min (15 min method). MS (m/z): 1033.5 (M+Na)⁺.

Example 11. Preparation of huMOV19-14

A reaction containing 2.0 mg/mL huMOV19 antibody and 8 molar equivalentscompound 14 (pretreated with 5-fold excess of sodium bisulfite in 90:10DMA:water) in 50 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) pH 8.5 buffer and 15% v/v DMA(N,N-Dimethylacetamide) cosolvent was allowed to conjugate for 6 hoursat 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 250mM Glycine, 10 mM Histidine, 1% sucrose, 0.01% Tween-20, 50 μM sodiumbisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). Dialysis wasperformed in the same buffer for 20 hours at 4° C. utilizingSlide-a-Lyzer dialysis cassettes (ThermoScientific 20,000 MWCO).

The purified conjugate was found to have an average of 3.0 IGN91molecules linked per antibody (by UV-Vis using molar extinctioncoefficients ε_(330 nm)=15,280 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹for compound 14, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody),90% monomer (by size exclusion chromatography), <0.1% unconjugatedcompound 14 (by acetone precipitation, reverse-phase HPLC analysis) anda final protein concentration of 0.78 mg/ml. The conjugated antibody wasfound to be >87% intact by gel chip analysis. The MS spectrometry datais shown in FIG. 7A.

Example 12. Preparation of huMOV19-sulfo-SPDB-98

An in situ mix containing final concentrations of 3.9 mM compound 98 and3 mM sulfo-SPDB linker in DMA containing 10 mM N,N-Diisopropylethylamine (DIPEA) was incubated for 60 min before adding 20-fold excess ofthe resulting compound 98-sulfo-SPDB-NHS to a reaction containing 4mg/ml huMOV19 antibody in 15 mM HEPES pH 8.5 (90:10 water: DMA). Thesolution was allowed to conjugate overnight at 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 100mM Arginine, 20 mM Histidine, 2% sucrose, 0.01% Tween-20, 50 μM sodiumbisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). Dialysis wasperformed in the same buffer over night at 4° C. utilizing Slide-a-Lyzerdialysis cassettes (ThermoScientific 10,000 MWCO).

The purified conjugate was found to have an average of 3.7 molecules ofcompound 98 linked per antibody (by SEC using molar extinctioncoefficients ε_(330 nm)=15,484 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹for compound 98, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody),99% monomer (by size exclusion chromatography), and a final proteinconcentration of 0.18 mg/ml. The MS spectrometry data is shown in FIG.7A.

Example 13. Preparation of huMOV19-35

A reaction containing 2.5 mg/mL huMOV19 antibody and 5 molar equivalentsof compound 35, (pretreated with 5-fold excess of sodium bisulfite in90:10 DMA:water) in 50 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) pH 8.5 buffer and 15% v/v DMA(N,N-Dimethylacetamide) cosolvent was allowed to conjugate for 6 hoursat 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 250mM Glycine, 10 mM Histidine, 1% sucrose, 0.01% Tween-20, 50 μM sodiumbisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). Dialysis wasperformed in the same buffer for 8 hours at room temperature utilizingSlide-a-Lyzer dialysis cassettes (ThermoScientific 10,000 MWCO).

The purified conjugate was found to have an average of 2.9 molecules ofcompound 35 linked per antibody (by UV-Vis using molar extinctioncoefficients ε_(330 nm)=15,484 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹for IGN128, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody), 97%monomer (by size exclusion chromatography), <1% unconjugated compound 35(by acetone precipitation, reverse-phase HPLC analysis) and a finalprotein concentration of 1.4 mg/ml. The MS spectrometry data is shown inFIG. 7A.

Example 14. Preparation of huMOV19-63

A reaction containing 2.0 mg/mL huMOV19 antibody and 7 molar equivalentsof compound 63 (pretreated with 5-fold excess of sodium bisulfite in90:10 DMA:water) in 50 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) pH 8.5 buffer and 15% v/v DMA(N,N-Dimethylacetamide) cosolvent was allowed to conjugate for 6 hoursat 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 250mM Glycine, 10 mM Histidine, 1% sucrose, 0.01% Tween-20, 50 μM sodiumbisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). Dialysis wasperformed in the same buffer for 20 hours at 4° C. utilizingSlide-a-Lyzer dialysis cassettes (ThermoScientific 20,000 MWCO).

The purified conjugate was found to have an average of 2.7 molecules ofcompound 63 linked per antibody (by UV-Vis using molar extinctioncoefficients ε_(330 nm)=15,280 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹for IGN131, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody), 99%monomer (by size exclusion chromatography), <0.1% unconjugated compound63 (by acetone precipitation, reverse-phase HPLC analysis) and a finalprotein concentration of 1.6 mg/ml. The conjugated antibody was found tobe >90% intact by gel chip analysis. The MS spectrometry data is shownin FIG. 7B.

Example 15. Preparation of huMOV19-80

A reaction containing 2.0 mg/mL huMOV19 antibody and 7 molar equivalentsof compound 80 (pretreated with 5-fold excess of sodium bisulfite in90:10 DMA:water) in 50 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) pH 8.5 buffer and 15% v/v DMA(N,N-Dimethylacetamide) cosolvent was allowed to conjugate for 6 hoursat 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 250mM Glycine, 10 mM Histidine, 1% sucrose, 0.01% Tween-20, 50 μM sodiumbisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). Dialysis wasperformed in the same buffer for 20 hours at 4° C. utilizingSlide-a-Lyzer dialysis cassettes (ThermoScientific 20,000 MWCO).

The purified conjugate was found to have an average of 2.5 molecules ofcompound 80 linked per antibody (by UV-Vis using molar extinctioncoefficients ε_(330 nm)=15,280 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹for compound 80, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody),99% monomer (by size exclusion chromatography), <0.1% unconjugatedcompound 80 (by acetone precipitation, reverse-phase HPLC analysis) anda final protein concentration of 2.4 mg/ml. The conjugated antibody wasfound to be >90% intact by gel chip analysis.

Example 16. Preparation of huMOV19-90

A reaction containing 2.0 mg/mL huMOV19 antibody and 3.9 molarequivalents of compound 90 (pretreated with 5-fold excess of sodiumbisulfite in 95:5 DMA:50 mM succinate pH 5.5 for 4 hours at 25° C.) in15 mM HEPES (4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid) pH 8.5buffer and 15% v/v DMA (N,N-Dimethylacetamide) cosolvent was incubatedfor 4 hours at 25° C. Post-reaction, the conjugate was purified andbuffer exchanged into 10 mM succinate, 50 mM sodium chloride, 8.5% w/vsucrose, 0.01% Tween-20, 50 μM sodium bisulfite pH 6.2 formulationbuffer using NAP desalting columns (Illustra Sephadex G-25 DNA Grade, GEHealthcare). Dialysis was performed in the same buffer for 4 hours atroom temperature and then overnight at 4° C. utilizing Slide-a-Lyzerdialysis cassettes (ThermoScientific 30,000 MWCO).

The purified conjugate was found to have a final protein concentrationof 1.8 mg/ml and an average of 2.7 molecules of compound 90 linked perantibody (by UV-Vis using molar extinction coefficientsε_(330 nm)=15,280 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹ for IGN152, andε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody); 98.3% monomer (by sizeexclusion chromatography); and <1.1% unconjugated compound 90 (byacetone precipitation, reverse-phase HPLC analysis). The MS spectrometrydata is shown in FIG. 7B.

Example 17. Preparation of huMOV19-49

A reaction containing 2.0 mg/mL huMOV19 antibody and 5 molar equivalentsof compound 49 (pretreated with 5-fold excess of sodium bisulfite in90:10 DMA:water) in 50 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) pH 8.5 buffer and 10% v/v DMA(N,N-Dimethylacetamide) cosolvent was allowed to conjugate for 4 hoursat 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 250mM Glycine, 10 mM Histidine, 1% sucrose, 0.01% Tween-20, 50 μM sodiumbisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). Dialysis wasperformed in the same buffer for 4 hours at room temperature utilizingSlide-a-Lyzer dialysis cassettes (ThermoScientific 20,000 MWCO).

The purified conjugate was found to have an average of 2.8 molecules ofcompound 49 linked per antibody (by UV-Vis using molar extinctioncoefficients ε_(330 nm)=15,280 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹for compound 49, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody),94% monomer (by size exclusion chromatography), <0.1% unconjugatedcompound 49 (by acetone precipitation, reverse-phase HPLC analysis) anda final protein concentration of 1.5 mg/ml. The conjugated antibody wasfound to be >95% intact by gel chip analysis. The MS spectrometry datais shown in FIG. 7C.

Example 18. Preparation of huMOV19-sulfo-SPDB-99

An in situ mix containing final concentrations of 1.95 mM compound 99and 1.5 mM sulfo-SPDB Linker in DMA containing 10 mMN,N-Diisopropylethyl amine (DIPEA) was incubated for 20 min beforecapping with 4 mM maleimidopropionic acid MPA. A 6-fold excess of theresulting 99-sulfo-SPDB-NHS was added to a reaction containing 2.5 mg/mlhuMOV19 antibody in 15 mM HEPES pH 8.5 (82:18 water:DMA). The solutionwas allowed to conjugate over night at 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 20mM histidine, 50 mM sodium chloride, 8.5% sucrose, 0.01% Tween-20, 50 μMsodium bisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). Dialysis wasperformed in the same buffer over night at 4° C. utilizing Slide-a-Lyzerdialysis cassettes (ThermoScientific 10,000 MWCO).

The purified conjugate was found to have an average of 1.6 molecules ofcompound 99 linked per antibody (by UV/Vis using molar extinctioncoefficients ε_(330 nm)=15,484 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹for compound 99, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody),99% monomer (by size exclusion chromatography), and a final proteinconcentration of 0.59 mg/ml. The MS spectrometry data is shown in FIG.7C.

Example 19. Preparation of huMOV19-70

A reaction containing 2.0 mg/mL huMOV19 antibody and 5 molar equivalentsof compound 70 (pretreated with 5-fold excess of sodium bisulfite in90:10 DMA:water) in 50 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) pH 8.5 buffer and 10% v/v DMA(N,N-Dimethylacetamide) cosolvent was allowed to conjugate for 4 hoursat 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 20mM Histidine, 100 mM Arginine, 2% sucrose, 0.01% Tween-20, 50 μM sodiumbisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). After purification,dialysis was performed in the same buffer for 18 hours at 4° C.utilizing Slide-a-Lyzer dialysis cassettes (ThermoScientific 20,000MWCO).

The purified conjugate was found to have an average of 3.0 molecules ofcompound 70 linked per antibody (by UV-Vis using molar extinctioncoefficients ε_(330 nm)=15,484 cm⁻¹M⁻¹ and ε_(280 nm)=30,115 cm⁻¹M⁻¹ forcompound 70, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody), 94%monomer (by size exclusion chromatography), <0.1% unconjugated compound70 (by acetone precipitation, reverse-phase HPLC analysis) and a finalprotein concentration of 1.3 mg/ml.

Example 20. Preparation of huMOV19-23

A reaction containing 2.5 mg/mL huMOV19 antibody and 4 molar equivalentsof compound 23 (pretreated with 5-fold excess of sodium bisulfite in90:10 DMA:water) in 50 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) pH 8.5 buffer and 15% v/v DMA(N,N-Dimethylacetamide) cosolvent was allowed to conjugate for 6 hoursat 25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 250mM Glycine, 10 mM Histidine, 1% sucrose, 0.01% Tween-20, 50 μM sodiumbisulfite formulation buffer pH 6.2 using NAP desalting columns(Illustra Sephadex G-25 DNA Grade, GE Healthcare). Dialysis wasperformed in the same buffer for 8 hours at room temperature utilizingSlide-a-Lyzer dialysis cassettes (ThermoScientific 10,000 MWCO).

The purified conjugate was found to have an average of 2.8 molecules ofcompound 23 linked per antibody (by UV-Vis using molar extinctioncoefficients ε_(330 nm)=15,484 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115 cm⁻¹M⁻¹for compound 23, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19 antibody),98% monomer (by size exclusion chromatography), <3% unconjugatedcompound 23 (by acetone precipitation, reverse-phase HPLC analysis) anda final protein concentration of 1.3 mg/ml. The MS spectrometry data isshown in FIG. 7D.

Example 21. Flow Cytometry Assay for Binding Affinity of huMOV19-14,huMOV19-90 and huMOV19-107 Conjugates

100 μl/well of the conjugate huMOV19-14, huMOV19-90 or huMOV19-107 orthe antibody huMOV19 were diluted in FACS buffer (1% BSA, 1×PBS) in a96-well plate (Falcon, round bottom) at a starting concentration of3×10⁻⁸ M in duplicate and serially diluted 3-fold in FACS buffer at 4°C. T47D cells (human breast tumor) grown in RPMI-1640 (LifeTechnologies) supplemented with heat-inactivated 10% FBS (LifeTechnologies), 0.1 mg/ml gentamycin (Life Technologies) and 0.2 IUbovine insulin/ml (Sigma) were washed once in PBS and removed withversene (Life Technogies). T47D cells were resuspended in growth media(see above) to neutralize versene and counted on a Coulter counter.Cells were then washed twice in cold FACS buffer, centrifuging inbetween washes at 1200 rpm for 5 min. 100 μl/ml of 2×10⁴ cells/well wereadded to wells containing the conjugate, antibody or FACS buffer onlyand incubated at 4° C. for 2 hr. After incubation, cells werecentrifuged as before and washed once in 200 μl/well cold FACS buffer.Cells were then stained with 200 μl/well FITC-conjugated GoatAnti-Human-IgG-Fcγ secondary antibody (controls included were unstainedcells and those stained with secondary antibody only) for 40 min at 4°C., centrifuged and washed once in 200 μl/well cold PBS-D. Cells werefixed in 200 μl/well 1% formaldehyde/PBS-D and stored at 4° C. Afterstorage, cellular surface staining of conjugate or antibody was detectedusing flow cytotometry on a FACS Calibur (BD Biosciences). The geometricmeans were plotted against the log concentration of the conjugate orantibody using GraphPad Prism and the EC₅₀ was calculated via non-linear4-parameter logistic regression analysis.

The binding assay was repeated for huMOV19-90 conjugate and the data isshown in FIG. 15B.

As shown in FIG. 1, FIG. 15A, FIG. 15B and FIG. 20, the conjugates bindssimilarly to the surface of T47D cells expressing the target antigen asthe unconjugated antibody in flow cytotometry, thereby demonstratingthat binding is not affected by the conjugation process.

Example 22. Cytotoxicity Assay for huMOV19-14 Conjugate

100 μl/well of huMOV19-14 conjugate was diluted in RPMI-1640 (LifeTechnologies) supplemented with heat-inactivated 10% FBS (LifeTechnologies) and 0.1 mg/ml gentamycin (Life Technologies) in a 96-wellplate (Corning, flat bottom) at starting concentrations of 3.5×10⁻⁹M to3.5×10⁻⁸ M in triplicate and serially diluted 3-fold in media above atambient temperature. KB cells (buccal epithelial tumor) grown in EMEM(ATCC) supplemented with heat-inactivated 10% FBS (Life Technologies)and 0.1 mg/ml gentamycin (Life Technologies) were washed once in PBS andremoved with 0.05% trypsin-EDTA (Life Technogies). KB cells wereresuspended in growth media (see above) to neutralize trypsin andcounted on a Coulter counter. 100 μl/ml of 1×10³ cells/well were addedto wells containing the conjugate or media only and incubated in a 37°C. incubator with 5% CO₂ for 5 days with and without 1 μM blockinganti-FOLR1 antibody (huMOV19). Total volume is 200 μl/well. Afterincubation, cell viability was analyzed by addition of 20 μl/well WST-8(Dojindo) and allowed to develop for 2 hr. Absorbance was read on aplate reader at 450 and 620 nm. Absorbances at 620 nm were subtractedfrom absorbances at 450 nm. Background in wells containing media onlywas further subtracted from corrected absorbances and surviving fraction(SF) of untreated cells was calculated in Excel. An XY graph of ADCconcentration (M) vs. SF was created using Graph Pad Prism.

As shown in FIG. 2, the conjugate is highly potent against the KB cellswith an IC₅₀ of 4×10⁻¹² M. Addition of an excess of unconjugatedantibody significantly reduce the cytotoxic effect, demonstratingantigen-specificity.

Example 23. Bystander Cytotoxicity Assay for huMOV19-14 and huMOV19-90Conjugates

100 μl/well of huMOV19-14 or huMOV19-90 was diluted in RPMI-1640 (LifeTechnologies) supplemented with heat-inactivated 10% FBS (LifeTechnologies), 0.1 mg/ml gentamycin (Life Technologies) and βME (LifeTechnologies) in a 96-well plate (Falcon, round bottom) atconcentrations between 1 e-10 M to 4 e-10 M in sextuplicate. Both 300.19cells (mouse) expressing recombinant FOLR1 (FR1#14) or no expressionvector (parental) were counted on a Coulter counter. 50 μl/ml of 1000FR1#14 cells/well were added to wells containing the conjugate or mediaonly, 50 μl/ml of 2000 parental cells/well were added to wellscontaining the conjugate or media only and both FR1#14 and parentalcells were added together to wells containing the conjugate or mediaonly. All plates were incubated in a 37° C. incubator with 5% CO₂ for 4days. Total volume was 150 μl/well. After incubation, cell viability wasanalyzed by addition of 75 μl/well Cell Titer Glo (Promega) and allowedto develop for 45 min. Luminescence was read on a luminometer andbackground in wells containing media only was subtracted from allvalues. A bar graph of the average of each cell treatment was graphedusing Graph Pad Prism.

As shown in FIG. 3, the conjugate huMOV19-14 exhibits weak bystandercytotoxic effect on the neighboring antigen-negative cells.

As shown in FIG. 13, the conjugate huMov19-90 exhibits strong bystanderkilling activity.

Example 24. In Vitro Cytotoxicity Assay for huMy9-6-14 Conjugate

Dilutions of conjugates were added to wells of 96-well plates containing2×10³ to 1×10⁴ cells per well in appropriate growth media. Control wellscontaining cells and the medium but lacking test compounds, as well aswells contained medium only, were included in each assay plate. Theplates were incubated for four to six days at 37° C. in a humidifiedatmosphere containing 6% CO₂. WST-8 reagent, 10% v/v, (Dojindo MolecularTechnologies, Gaithersburg, Md.), was then added to the wells, and theplates were incubated at 37° C. for 2 to 6 h. Then the absorbance wasmeasured on a plate-reader spectrophotometer in the dual wavelength mode450 nm/650 nm, and the absorbance at the 650 nm (non-specific lightscattering by cells) was subtracted. The apparent surviving fraction ofcells in each well was calculated by first correcting for the mediumbackground absorbance, and then dividing each value by the average ofthe values in the control wells (non-treated cells).

As shown in FIG. 3, the conjugate is highly potent against variousantigen positive cancer cells; while antigen negative L-540 cells remainviable when exposed to the same conjugate.

Example 25. Bystander Cytotoxicity Assay for huMy9-6-14 Conjugate

Preliminary tests were done to determine the concentration of huMy9-6-14that was not cytotoxic to the antigen-negative RADA-1 cells, but killedall of the antigen-positive KARA cells. RADA-1 (500 cells per well) andKARA (500, 1000, 2000, 4000 cells per well) were plated in 96-well roundbottomed plates. Dilutions of huMy9-6-14 were prepared in the cellculture medium (RPMI1640 medium supplemented with 10% heat inactivatedfetal bovine serum and 50 mg/L gentamicin) and added to the cells.Plates were incubated for 4 days at 37° C., and viability of the cellsin each well was determined using WST-8 reagent (Dojindo MolecularTechnologies, Inc.). To test the bystander potency of the conjugates,RADA-1 and KARA cells were mixed together at different ratios (500RADA-1 cells plus no KARA cells; 500 RADA-1 cells plus 500 KARA cells;500 RADA-1 cells plus 1000 KARA cells; 500 RADA-1 cells plus 2000 KARAcells; 500 RADA-1 cells plus 4000 KARA cells), and plated in 96-wellround bottomed plates. Then 1.0e-9M or 5.0e-10M of huMy9-6-14—theconcentrations that were not cytotoxic to RADA-1 cells but killed allKARA cells—were added to the cell mixtures. Plates were incubated for 4days at 37° C., and viability of RADA-1 cells in each well wasdetermined using WST-8 reagent (Dojindo Molecular Technologies, Inc.).The absorbance was measured on a plate-reader spectrophotometer in thedual wavelength mode 450 nm/650 nm, and the absorbance at the 650 nm(non-specific light scattering by cells) was subtracted.

As shown in FIG. 5, the conjugate exhibits bystander killing effect onthe neighboring antigen-negative cells.

Example 26. Antitumor Activity of Single-Dose huMOV19-80 and huMOV19-90Against NCI-H2110 NSCLC Xenografts in Female SCID Mice

Female CB.17 SCID mice, 6 weeks old, were received from Charles RiverLaboratories. Mice were inoculated with 1×10⁷ NCI-H2110 tumor cellssuspended in 0.1 ml 50% matrigel/serum free medium by subcutaneousinjection in the right flank. When tumor volumes reached approximately100 mm³ (day 7 post inoculation), animals were randomized based on tumorvolume into 5 groups of 6 mice each. Mice received a single IVadministration of vehicle control (0.2 ml/mouse), huMOV19-80 orhuMOV19-90 at 5 and 25 μg/kg based on huMOV19-80 or huMOV19-90concentration on day 1 (day 8 post inoculation). huMOV19 is a humanizedmonoclonal antibody that selectively binds to folate receptor 1 (FOLR1).

Tumor size was measured twice to three times weekly in three dimensionsusing a caliper. The tumor volume was expressed in mm³ using the formulaV=Length×Width×Height×½. A mouse was considered to have a partialregression (PR) when tumor volume was reduced by 50% or greater,complete tumor regression (CR) when no palpable tumor could be detected.Tumor volume was determined by StudyLog software. Tumor growthinhibition (T/C Value) was determined using the following formula:

T/C (%)=Median tumor volume of the treated/Median tumor volume of thecontrol×100.

Tumor volume was determined simultaneously for treated (T) and thevehicle control (C) groups when tumor volume of the vehicle controlreached predetermined size of 1000 mm³. The daily median tumor volume ofeach treated group was determined, including tumor-free mice (0 mm³).According to NCI standards, a T/C≦42% is the minimum level of anti-tumoractivity. A T/C≦10% is considered a high anti-tumor activity level.

As shown in FIG. 6, the huMOV19-90 conjugate is highly active at both 5and 25 μg/kg dose; while huMOV19-80 conjugate is highly active at 25μg/kg dose.

Example 27. Preparation of huML66-90

A reaction containing 2.0 mg/mL huML66 antibody, an anti-EGFR antibody(see WO 2012/058592, incorporated herein by reference in its entirety),and 3.5 molar equivalents compound 90 (pretreated with 5-fold excess ofsodium bisulfite in 90:10 DMA:50 mM succinate pH 5.5 for 4 hours at 25°C.) in 15 mM HEPES (4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid)pH 8.5 buffer and 10% v/v DMA (N,N-Dimethylacetamide) cosolvent wasincubated for 4 hours at 25° C. Post-reaction, the conjugate waspurified and buffer exchanged into 20 mM histidine, 50 mM sodiumchloride, 8.5% w/v sucrose, 0.01% Tween-20, 50 μM sodium bisulfite pH6.2 formulation buffer using NAP desalting columns (Illustra SephadexG-25 DNA Grade, GE Healthcare). Dialysis was performed in the samebuffer for 4 hours at room temperature and then overnight at 4° C.utilizing Slide-a-Lyzer dialysis cassettes (ThermoScientific 30,000MWCO).

The purified conjugate was found to have a final protein concentrationof 0.9 mg/ml and an average of 2.7 molecules of compound 90 linked perantibody (by UV-Vis using molar extinction coefficientsε_(330 nm)=15,280 cm-1M-1 and ε_(280 nm)=30, 115 cm-1M-1 for compound90, and ε_(280 nm)=205,520 cm-1M-1 for huML66 antibody); 99.1% monomer(by size exclusion chromatography); and <1% unconjugated IGN149 (dualcolumn, reverse-phase HPLC analysis). The MS spectrometry data is shownin FIG. 8.

Example 28. In Vitro Cytotoxic Assays for huML66-90 Conjugate

The ability of huML66-90 conjugate to inhibit cell growth was measuredusing in vitro cytotoxicity assays. Target cells were plated at 1-2,000cells per well in 100 μL in complete RPMI media (RPMI-1640, 10% fetalbovine serum, 2 mM glutamine, 1% penicillin-streptomycin, all reagentsfrom Invitrogen). Antibodies were diluted into complete RPMI media using3-fold dilution series and 100 μL were added per well. The finalconcentration typically ranged from 3×10-8 M to 4.6×10-12 M. Cells wereincubated at 37° C. in a humidified 5% CO2 incubator for 5-6 days.Viability of remaining cells was determined by colorimetric WST-8 assay(Dojindo Molecular Technologies, Inc., Rockville, Md., US). WST-8 isreduced by dehydrogenases in living cells to an orange formazan productthat is soluble in tissue culture medium. The amount of formazanproduced is directly proportional to the number of living cells. WST-8was added to 10% of the final volume and plates were incubated at 37° C.in a humidified 5% CO2 incubator for an additional 2-4 hours. Plateswere analyzed by measuring the absorbance at 450 nm (A450) in amultiwell plate reader. Background A450 absorbance of wells with mediaand WST-8 only was subtracted from all values. The percent viability wascalculated by dividing each treated sample value by the average value ofwells with untreated cells. Percent viability=100*(A450 treatedsample−A450 background)/(A450 untreated sample−A450 background). Thepercent viability value was plotted against the antibody concentrationin a semi-log plot for each treatment. Dose-response curves weregenerated by non-linear regression and the EC₅₀ value of each curve wascalculated using GraphPad Prism (GraphPad software, San Diego, Calif.).

In Vitro Cytotoxic Activity

The in vitro cytotoxicity of huML66-90 conjugate was evaluated in thepresence and absence of excess unconjugated antibody and compared to theactivity of a non-specific huIgG-90 conjugate in EGFR-expressing cellsand the results from a typical cytotoxicity assay are shown in FIG. 9.The huML66-90 conjugate resulted in specific cell killing of Detroit-562SCC-HN cells with an EC₅₀ value of 16 μM. The presence of excessunconjugated antibody significantly reduced activity and resulting in anEC₅₀ value of approximately 2 nM. Similarly, huIgG-90 conjugate with anon-binding huIgG control antibody resulted in cell killing with an EC₅₀value of approximately 8 nM.

Likewise, the huML66-90 conjugate resulted in specific cell killing ofNCI-H292 NSCLC cells with an EC₅₀ value of 12 pM. The presence of excessunconjugated antibody significantly reduced activity and resulting in anEC₅₀ value of approximately 2 nM. Similarly, huIgG-90 conjugate with anon-binding huIgG control antibody resulted in cell killing with an EC₅₀value of approximately 8 nM.

Similarly, specific cell killing of NCI-H1703 cells were also observed.

TABLE 1 Detroit NCI-H292 NCI-H1703 Conjugate EC₅₀ in pM EC₅₀ in pM EC₅₀in pM huML66-90 16 12 20 huML66-90 + block 2,350 1,570 2,140 huIgG-90ctrl 8,350 8,350 N/A

Example 29. In Vitro Cytotoxic Activity for huMOV19-90

100 μl/well of huMOV19-90 conjugate was each diluted in RPMI-1640 (LifeTechnologies) supplemented with heat-inactivated 10% FBS (LifeTechnologies) and 0.1 mg/ml gentamycin (Life Technologies) in a 96-wellplate (Corning, flat bottom) at starting concentrations of 3.5e-9 M andto 3.5 e-8 M in triplicate and serially diluted 3-fold in media above atambient temperature. KB cells (buccal epithelial tumor), grown in EMEM(ATCC) supplemented with heat-inactivated 10% FBS (Life Technologies)and 0.1 mg/ml gentamycin (Life Technologies), were washed once in PBSand removed with 0.05% trypsin-EDTA (Life Technogies). Other cellstested were NCI-H2110 (NSCLC) and T47D (breat epthelial) grown inRPMI-1640 (LifeTechnologies) supplemented with heat-inactivated 10% FBS(Life Technologies) and 0.1 mg/ml gentamycin (Life Technologies). T47Dmedia also was supplemented with 0.2 IU/ml bovine insulin. All cellswere resuspended in growth media (see above) to neutralize trypsin andcounted using a hemacytometer. 100 μl/ml of 1000 KB cells/well or 2000T47D and NCI-H2110 cells/well were added to wells containing theconjugate or media only and incubated in a 37° C. incubator with 5% CO₂for 5 days with and without 1 μM blocking anti-FOLR1 antibody (huMOV19).Total volume is 200 μl/well. The starting concentration of eachconjugate on KB cells was 3.5e-9 M and for T47D and NCI-H2110 cells, thestarting concentration of each conjugate was 3.5e-8 M. After incubation,cell viability was analyzed by addition of 20 μl/well WST-8 (Dojindo)and allowed to develop for 2 hr. Absorbance was read on a plate readerat 450 and 620 nm. Absorbances at 620 nm were subtracted fromabsorbances at 450 nm. Background in wells containing media only wasfurther subtracted from corrected absorbances and surviving fraction(SF) of untreated cells was calculated in Excel. An XY graph of ADCconcentration (M) vs. SF was created using Graph Pad Prism.

As shown in FIGS. 10-12 and Table 2, the huMOV19-90 conjugate is highlypotent against the KB cells, T47 D cells and NCI-H2110 cells. Additionof an excess of unconjugated antibody significantly reduce the cytotoxiceffect, demonstrating antigen-specificity.

TABLE 2 KB NCI-H2110 T47D −Block +Block −Block +Block −Block +Block IC₅₀4e−12M 8e−10M 2e−11M 1e−8M 3e−11M 8e−9M

In another experiment, the ability of the conjugates to inhibit cellgrowth was measured using a WST-8-based in vitro cytotoxicity assay.Cells in 96-well plates (typically, 1×10³ per well) were treated withthe conjugate at various concentrations in an appropriate cell culturemedium with a total volume of 0.2 ml. Control wells containing cells andthe medium but lacking test compounds, and wells containing medium only,were included in each assay plate. The plates were incubated for 4 to 6days at 37° C. in a humidified atmosphere containing 6% CO₂. WST-8reagent (10%, volume/volume; Dojindo Molecular Technologies) was thenadded to the wells, and the plates were incubated at 37° C. for 2 to 6hours depending on a cell line. Then, the absorbance was measured on aplate reader spectrophotometer in the dual-wavelength mode 450 nm/620nm, and the absorbance at the 620 nm (nonspecific light scattering bycells) was subtracted. The resulting OD₄₅₀ values were utilized tocalculate apparent surviving fractions of cells using GraphPad Prism v4(GraphPad software, San Diego, Calif.). The apparent surviving fractionof the cells in each well was calculated by first correcting for themedium background absorbance and then dividing each value by the averageof the values in the control wells (non-treated cells). Dose responsecurves were generated by non-linear regression using a sigmoidal curvefit with variable slope in Graph Pad Prism. IC₅₀ (inhibitoryconcentration 50%) was generated by the software.

The conjugates were active against the tested cell lines Ishikawa(endometrial cancer), KB (cervical cancer) and NCI-H2110 (non-small celllung carcinoma) as shown in FIG. 21 and Table 3. The cell-killingactivity was FOLR1-dependent, since an excess of unmodified huMOV19antibody (1 μM) markedly decreased potency of the conjugate (from 20 to200-fold).

TABLE 3 IC50, nM huMOV19-90 huMOV19-107 Conjugate + Conjugate + Cellunmodified unmodified line Conjugate antibody Conjugate antibodyIshikawa 0.05 1.0 0.05 2.0 KB 0.005 1.0 0.005 0.8 NCI-H2110 0.1 4.0 0.17.0

Example 30. Antitumor Activity of Single-Dose huMOV19-90 ConjugateAgainst NCI-H2110 NSCLC Xenografts in Female SCID Mice

Female CB.17 SCID mice, 6 weeks old, were received from Charles RiverLaboratories. Mice were inoculated with 1×107 NCI-H2110 tumor cellssuspended in 0.1 ml 50% matrigel/serum free medium by subcutaneousinjection in the right flank. When tumor volumes reached approximately100 mm³ (day 7 post inoculation), animals were randomized based on tumorvolume into 4 groups of 6 mice each. Mice received a single IVadministration of vehicle control (0.2 ml/mouse) or huMOV19-90 at 1, 3or 5 g/kg based on concentration of compound 90 on day 1 (day 8 postinoculation).

Tumor size was measured twice to three times weekly in three dimensionsusing a caliper. The tumor volume was expressed in mm³ using the formulaV=Length×Width×Height×½. A mouse was considered to have a partialregression (PR) when tumor volume was reduced by 50% or greater,complete tumor regression (CR) when no palpable tumor could be detected.Tumor volume was determined by StudyLog software.

Tumor growth inhibition (T/C Value) was determined using the followingformula:

T/C (%)=Median tumor volume of the treated/Median tumor volume of thecontrol×100.

Tumor volume was determined simultaneously for treated (T) and thevehicle control (C) groups when tumor volume of the vehicle controlreached predetermined size of 1000 mm3. The daily median tumor volume ofeach treated group was determined, including tumor-free mice (0 mm3).According to NCI standards, a T/C≦42% is the minimum level of anti-tumoractivity. A T/C<10% is considered a high anti-tumor activity level.

As shown in FIG. 14, the huMOV19-90 conjugate is active at 3 μg/kg doseand is highly active at 5 μg/kg dose.

Example 31. Synthesis of Compound 107

Step 1:

Compound 82 (500 mg, 2.31 mmol), 4-methyl-4-(methyldisulfanyl)pentanoicacid (449 mg, 2.31 mmol), EDC.HCl (465 mg, 2.43 mmol), HOBt (354 mg,2.31 mmol), and DIPEA (0.81 mL, 4.62 mmol) were dissolved in DMF (7.7mL) and stirred overnight until the reaction was complete. The reactionwas diluted with ethyl acetate and washed with saturated sodiumbicarbonate, saturated ammonium chloride, and twice with water. Theorganic was dried and concentrated in vacuo to give compound 100 (875mg, 96% yield) which was used directly in the next step. ¹H NMR (400MHz, DMSO): δ 8.15 (d, 1H, J=6.8 Hz), 8.02 (d, 1H, J=6.8 Hz), 4.26-4.33(m, 1H), 4.03-4.12 (m, 1H), 2.41 (s, 3H), 2.18-2.22 (m, 2H), 1.76-1.80(m, 2H), 1.39 (s, 9H), 1.24 (s, 6H), 1.24 (d, 3H, J=7.2 Hz), 1.19 (d,3H, J=7.2 Hz).

Step 2:

TFA (2.6 ml) and water (0.17 ml) were added to neat Compound 100 (875mg, 2.23 mmol) and were stirred at room temperature until the reactionwas complete. The reaction was diluted and azeotroped with acetonitrileto obtain a sticky oil. It was then diluted with acetonitrile and water,frozen and lyophilized to give compound 101 (1 g, 100% yield) as an offwhite solid that was used without further purification. LCMS=3.99 min (8min method). MS (m/z): 337.0 (M+1)⁺.

Step 3:

Compound 101 (923 mg, 1.65 mmol) and (5-amino-1,3-phenylene)dimethanol(240 mg, 1.57 mmol) were dissolved in DMF (5.2 ml). EDC.HCl (601 mg,3.13 mmol), and DMAP (96 mg, 0.78 mmol) were added at room temperatureand the reaction was stirred overnight at room temperature. The reactionwas diluted with ethyl acetate and washed with water three times. Theorganic layer was dried, concentrated in vacuo and purified by silicagel chromatography (DCM/MeOH) to give Compound 102 (150 mg, 20% yield).LCMS=3.91 min (8 min method). MS (m/z): 472.2 (M+1)⁺. ¹H NMR (400 MHz,MeOD): δ 9.69 (s, 1H), 8.21 (d, 1H, J=6.8 Hz), 8.18 (d, 1H, J=6.8 Hz),7.52 (s, 2H), 7.12 (s, 1H), 4.58 (s, 4H), 4.44-4.48 (m, 1H), 4.29-4.32(m, 1H), 3.34 (s, 2H), 2.38 (s, 3H), 2.34-2.40 (m, 2H), 1.90-1.95 (m,2H), 1.43 (d, 3H, J=7.2 Hz), 1.36 (d, 3H, J=7.2 Hz), 1.30 (s, 6H).

Step 4:

Compound 102 was prepared similarly as compound 94 in Example 9. Thecrude material was dried under high vacuumed to give Compound 103 (174mgs, 101% yield) that was used directly in the next step without furtherpurification. LCMS=4.95 min (8 min method).

Step 5:

Compound 103 was prepared similarly as compound 57 in Example 7. Thecrude solid contained compound 104 (203 mg, 44% yield, 60% purity) whichwas used without further purification. LCMS=5.68 min (8 min method). MS(m/z): 1024.3 (M+1)⁺.

Step 6:

Compound 104 was prepared similarly as compound 12 in Example 1. Thecrude residue was purified by RPHPLC (C18 column, CH₃CN/H₂O, gradient,50% to 65%) to yield mono imine compound 105 as a solid (22 mg, 16%yield, 90% pure). LCMS=6.00 min (8 min method). MS (m/z): 1027.3 (M+1)⁺.

Step 7:

Compound 106 was dissolved in THF (0.5 mL) and ACN (0.23 mL) at roomtemperature. It was then prepared similarly to compound 98 in Example 9.The mixture was stirred until completion and then diluted with DCM andDI water. The organic layer was washed with brine, dried and filtered.The filtrate was concentrated to give the crude thiol, compound 106 (21mg, 100% yield) which was used directly in the next reaction. LCMS=5.67min (8 min method). MS (m/z): 980.4 (M+1)+.

Step 8:

Compound 106 (21 mg, 0.021 mmol) was suspended in 2-propanol (1428 μl)and water (714 μl). Sodium metabisulfite (22.30 mg, 0.214 mmol) wasadded and the reaction stirred at room temperature until completion. Thereaction mixture was diluted with acetonitrile/water, frozen andlyophilized. The resulting white powder was purified by RPHPLC (C18column, CH₃CN/H₂O, gradient, 20% to 40%) and the desired fractions werecollected and lyophilized to give compound 107 (5.3 mg, 23% yield).LCMS=5.67 min (8 min method). MS (m/z): 1060.2 (M−1)⁻.

Example 32. Preparation of huMOV19-sulfo-SPDB-107 (or huMOV19-107)Conjugate

An in situ mix containing final concentrations of 1.95 mM Compound 107and 1.5 mM sulfo-SPDB Linker in succinate buffer (pH 5):DMA (30:70) wasincubated for 6 h before adding a 7-fold excess of 107-sulfo-SPDB-NHS toa reaction containing 4 mg/ml huMOV19 antibody in 15 mM HEPES pH 8.5(87:13, water:DMA). The solution was allowed to conjugate over night at25° C.

Post-reaction, the conjugate was purified and buffer exchanged into 10mM Tris, 80 mM NaCl, 50 uM Bisulfite, 3.5% Sucrose, 0.01% Tween-20formulation buffer pH 7.6 using NAP desalting columns (Illustra SephadexG-25 DNA Grade, GE Healthcare). Dialysis was performed in the samebuffer over night at 4° C. utilizing Slide-a-Lyzer dialysis cassettes(ThermoScientific 10,000 MWCO).

The purified conjugate was found to have an average of 2.7 molecules ofcompound 107 linked per antibody (by UV/Vis and SEC using molarextinction coefficients ε_(330 nm)=15,484 cm⁻¹M⁻¹ and ε_(280 nm)=30, 115cm⁻¹M⁻¹ for compound 107, and ε_(280 nm)=201,400 cm⁻¹M⁻¹ for huMOV19antibody), 95% monomer (by size exclusion chromatography), and a finalprotein concentration of 1.1 mg/ml. The MS spectrometry data is shown inFIG. 16.

Example 33. Antitumor Activity of Single-Dose huML66-90 ConjugateAgainst NCI-H1703 NSCLC Xenografts in Female SCID Mice

Female CB.17 SCID mice, 6 weeks old, were received from Charles RiverLaboratories. Mice were inoculated with 5×10⁶ NCI-H1703 tumor cellssuspended in 0.2 ml 50% matrigel/serum free medium by subcutaneousinjection in the right flank. When tumor volumes reached approximately100 mm³ (day 16 post inoculation), animals were randomized based ontumor volume into 4 groups of 6 mice each. Mice received a single IVadministration of vehicle control (0.1 ml/mouse) or huML66-90 conjugateat 5, 20 or 50 μg/kg based on compound 90 concentration on day 1 (day 17post inoculation).

Tumor size was measured twice to three times weekly in three dimensionsusing a caliper. The tumor volume was expressed in mm³ using the formulaV=Length×Width×Height×½. A mouse was considered to have a partialregression (PR) when tumor volume was reduced by 50% or greater,complete tumor regression (CR) when no palpable tumor could be detected.Tumor volume was determined by StudyLog software.

Tumor growth inhibition (T/C Value) was determined using the followingformula:

T/C (%)=Median tumor volume of the treated/Median tumor volume of thecontrol×100.

Tumor volume was determined simultaneously for treated (T) and thevehicle control (C) groups when tumor volume of the vehicle controlreached predetermined size of 1000 mm³. The daily median tumor volume ofeach treated group was determined, including tumor-free mice (0 mm³).According to NCI standards, a T/C≦42% is the minimum level of anti-tumoractivity. A T/C<10% is considered a high anti-tumor activity level.

As shown in FIG. 17, the huML66-90 conjugate is highly active at 20μg/kg and 50 μg/kg, with 20 μg/kg as minimal effective dose (MED).

Example 34. Pharmacokinetics of Single-Dose huMov19-90 Conjugate inFemale CD-1 Mice

Female CD-1 mice, 7 weeks old, were received from Charles RiverLaboratories. Mice received a single IV administration of huMov19-90conjugate as a single intravenous bolus injection via a lateral tailvein. Each mouse received a dose of 2.5 mg/kg based on Ab. The dose andinjected volume were individualized on the basis of the body weight ofeach mouse. Injections were carried out using a 1.0 mL syringe fittedwith a 27 gauge, ½ inch needle. At 2 and 30 min, and at 2, 4 and 8hours, and at 1, 2, 3, 5, 7, 10, 14, 21 and 28 days after administrationof the huMov19-90 conjugate, mice were anesthetized by isofluraneinhalation, and approximately 150 μL of blood was collected from micevia the right retro-orbital blood sinus into a heparinized capillarytube. At each time point (from 0 to 21 days), blood was collected fromall three mice in one group. Groups were bled in turn; so that the micein the set were not bled more than two times in a 24-hour period. At thefinal time point, 28 days post-administration, all mice were includedfor sample collection. Blood samples were centrifuged to separate theplasma. 30 μl plasma was transferred to individual labeledmicrocentrifuge tubes for each sample and time point, and then storedfrozen at −80° C. to allow subsequent analysis by ELISA to determineconcentrations of total Ab (both unconjugated Ab and intact conjugate)and intact conjugate using an anti-indolinobenzodiazepine antibody.

As shown in FIG. 18, the huMov19-90 conjugate has similar clearance tothat of the antibody.

Example 35. Catabolite Enrichment by Affinity Capture with Protein AResin

KB cells expressing folate receptor α (FRα) were cultured in 5×T150tissue culture plates. Saturating amount of FRα-targeting huMov19-90conjugate was incubated with KB cells for 24 hours at 37° C. in ahumidified incubator buffered with 5% CO₂. After 24 hours, the mediacontaining cell-effluxed catabolites were harvested and pooled for thefollowing assay.

Saturating amount of anti-indolinobenzodiazepine antibody was bound to aslurry of protein A resins by overnight incubation at 4° C. 1 mL ofpre-bound protein A/anti-indolinobenzodiazepine antibody complex wasincubated with 25 mL of media on an end-to-end rotator for severalhours. The resins were centrifuged gently at 1000 rpm, and thesupernatant was decanted. The protein-A/anti-indolinobenzodiazepineantibody resins bound to the catabolites were washed with PBS. Thecatabolites were released into organic phase by acetone extraction. Thecatabolites were vacuum-dried overnight until the organic solution wascompletely evaporated. The catabolites were reconstituted with 20%acetonitrile in water, and analyzed by LC/MS.

MS Analysis

Cell catabolites were identified by UHPLC/MS/MS using Q-Exactive highresolution mass spec (Thermo). Extracted ion-chromatograms (XIC) wereused to identify and characterize the target cell catabolites. Allcatabolite species containing the characteristic indolinobenzodiazepine(286 m/z) mass signatures were identified (see FIGS. 19A and 19B).

Example 36. Antitumor Activity of Single-Dose huMov19-90 AgainstNCI-H2110 NSCLC Xenografts, Hec-1b Endometrial Xenografts and IshikawaEndometrial Xenografts in Female CB.17 SCID Mice

Female CB.17 SCID mice, 6 weeks old, were received from Charles RiverLaboratories. One cohort of mice were inoculated with 1×10⁷ NCI-H2110tumor cells suspended in 0.1 ml 50% matrigel/serum free medium bysubcutaneous injection in the right flank. The second cohort of micewere inoculated with 1×10⁷ Hec-1b tumor cells suspended in 0.1 ml serumfree medium by subcutaneous injection in the right flank. The thirdcohort of mice were inoculated with 1×10⁷ Ishikawa tumor cells suspendedin 0.1 ml 50% matrigel/serum free medium by subcutaneous injection inthe right flank.

When tumor volumes reached approximately 100 mm³ (NCI-H2110 on day 7,Hec-1b on day 7, and Ishikawa on day 17 post inoculation), animals wererandomized based on tumor volume into groups of 6 mice each.

Mice in the NCI-H2110 xenograft experiment received a single IVadministration of vehicle control (0.2 ml/mouse) or huMov19-90 at 1, 3,or 5 μg/kg based on drug concentration on day 1 (day 8 postinoculation).

Mice in the Hec-1b xenograft experiment received a single IVadministration of vehicle control (0.2 ml/mouse) or huMov19-90 at 10 or30 μg/kg or the non-targeting control conjugate chKTI-90 at 30 μg/kgbased on drug concentration on day 1 (day 8 post inoculation).

Mice in the Ishikawa xenograft experiment received a single IVadministration of vehicle control (0.2 ml/mouse) or huMov19-90 at 10 or30 μg/kg or the non-targeting control conjugate chKTI-90 at 30 μg/kgbased on drug concentration on day 1 (day 18 post inoculation).

For all experiments, tumor size was measured twice to three times weeklyin three dimensions using a caliper. The tumor volume was expressed inmm³ using the formula V=Length×Width×Height×½. A mouse was considered tohave a partial regression (PR) when tumor volume was reduced by 50% orgreater, complete tumor regression (CR) when no palpable tumor could bedetected. Tumor volume was determined by StudyLog software.

Tumor growth inhibition (T/C Value) was determined using the followingformula:

T/C (%)=Median tumor volume of the treated/Median tumor volume of thecontrol×100.

Tumor volume was determined simultaneously for treated (T) and thevehicle control (C) groups when tumor volume of the vehicle controlreached predetermined size of 1000 mm³. The daily median tumor volume ofeach treated group was determined, including tumor-free mice (0 mm³).According to NCI standards, a T/C≦42% is the minimum level of anti-tumoractivity. A T/C<10% is considered a high anti-tumor activity level.

As shown in FIG. 22, the huMov19-90 conjugate was inactive in theNCI-H2110 xenograft model at a dose of 1 μg/kg, active at a dose of 3μg/kg with a T/C of 13% and 1/6 PRs and highly active at a dose of 5μg/kg with a T/C of 2%, 6/6 PRs and 4/6 CRs.

As shown in FIG. 23, the huMov19-90 conjugate was active in the Hec-1bxenograft model at a dose of 10 μg/kg with a T/C of 15% and 1/6 PRs andhighly active at a dose of 30 μg/kg with a T/C of 9%, 6/6 PRs and 6/6CRs. The non-targeting control conjugate chKTI-90 was active at a doseof 30 μg/kg with a T/C of 34%.

As shown in FIG. 24, the huMov19-90 conjugate was active in the Ishikawaxenograft model at a dose of 10 μg/kg with a T/C of 27%, 6/6 PRs and 6/6CRs and active at a dose of 30 μg/kg with a T/C of 15%, 6/6 PRs and 6/6CRs. The non-targeting control conjugate chKTI-90 was active at a doseof 30 μg/kg with a T/C of 24% and 4/6 PRs.

Example 37. Antitumor Activity of Single-Dose huMov19-107 AgainstNCI-H2110 NSCLC Xenografts, in Female CB.17 SCID Mice

In vivo antitumor activity of huMOV19-107 in SCID mice was conductedaccording to protocols described in Example 30 above. As shown in FIG.25, the huMov19-107 conjugate was highly active at 10 μg/kg dose and 6/6CRs.

Example 38. Binding Affinity of CD123-90 Conjugate

Binding affinity of the ADC conjugate of an exemplary humanizedanti-CD123 antibody, huCD123-6Gv4.7S3 antibody, was assayed and comparedto the corresponding unconjugated antibody by flow cytometry usingHNT-34 cells. HNT-34 cells (5×10⁴ cells per sample) were incubated withvarying concentrations of the ADC and the unconjugated huCD123-6Gv4.7S3antibody in 200 μL FACS buffer (DMEM medium supplemented with 2% normalgoat serum). The cells were then pelleted, washed twice, and incubatedfor 1 hr with 100 μL of phycoerythrin (PE)-conjugated goat anti-humanIgG-antibody (Jackson Laboratory). The cells were pelleted again, washedwith FACS buffer and resuspended in 200 μL of PBS containing 1%formaldehyde. Samples were acquired using a FACSCalibur flow cytometerwith the HTS multiwell sampler, or a FACS array flow cytometer, andanalyzed using CellQuest Pro (all from BD Biosciences, San Diego, US).For each sample the geomean fluorescence intensity for FL2 wascalculated and plotted against the antibody concentration in a semi-logplot. A dose-response curve was generated by non-linear regression andthe EC50 value of each curve, which corresponds to the apparentdissociation constant (Kd) of each antibody, was calculated usingGraphPad Prism v4 (GraphPad software, San Diego, Calif.).

As shown in FIG. 26, conjugation only moderately affected the bindingaffinity of the exemplary anti-CD123 antibody.

Example 39. In Vitro Cytotoxic Activity for huCD123-90

The ability of antibody-drug conjugates (ADC) of huCD123-6, ananti-CD123 antibody, to kill cells that express CD123 on their cellsurface was measured using in vitro cytotoxicity assays. The cell lineswere cultured in culture medium as recommended by the cell supplier(ATCC or DSMZ). The cells, 2,000 to 10,000 in 100 μL of the culturemedium, were added to each well of flat bottom 96-well plates. To blockFc receptors on the cell surface, the culture medium was supplementedwith 100 nM chKTI antibody (an antibody of the same isotype). Conjugateswere diluted into the culture medium using 3-fold dilution series and100 μL were added per well. To determine the contribution ofCD123-independent cytotoxicity, CD123 block (e.g., 100 nM of chCD123-6antibody) was added to some wells prior to the conjugates. Control wellscontaining cells and the medium but lacking the conjugates, as well aswells contained medium only, were included in each assay plate. Assayswere performed in triplicate for each data point. The plates wereincubated at 37° C. in a humidified 6% CO₂ incubator for 4 to 7 days.Then the relative number of viable cells in each well was determinedusing the WST-8 based Cell Counting Kit-8 (Dojindo MolecularTechnologies, Inc., Rockville, Md.). The apparent surviving fraction ofcells in each well was calculated by first correcting for the mediumbackground absorbance, and then dividing each value by the average ofthe values in the control wells (non-treated cells). The survivingfraction of cells was plotted against conjugate concentration insemi-log plots.

Fifteen CD123-positive cell lines of different origin (AML, B-ALL, CMLand NHL) were used in the study (Table 4). The majority of the celllines were derived from patients carrying a malignancy with at least onenegative prognostic factor (e.g., overexpression of P-glycoprotein,overexpression of EVI1, p53 alterations, DNMT3A mutation, FLT3 internaltandem duplication). The conjugates demonstrated high potency on thesecell lines with IC50 values ranging from sub-pM to low nM (Table 4).

TABLE 4 In vitro cytotoxicity of huCD123-6-90 conjugate againstCD123-positive cell lines of different origin Cell Line Origin NegativePrognostic Factor IC₅₀ (M) THP1 AML p53 deletion 6.7E−12 SHI-1 AML p53gene alterations 1.3E−11 KO52 AML p53 mutant, Pgp overexpression 1.4E−11KASUMI-3 AML EVI1 and Pgp overexpression 9.8E−12 KG-1 AML p53 mutant,Pgp overexpression 2.2E−10 OCI-AML2 AML DNMT3A mutation 8.8E−11 HNT-34AML MECOM (EVI1) overexpression 2.0E−12 MV4-11 AML FLT3 internal tademduplication 5.6E−13 MOLM-13 AML FLT3 internal tadem duplication 4.9E−13EOL-1 AML 2.5E−12 MOLM-1 CML EVI1 and Pgp overexpression 2.9E−11 KOPN8B-ALL 1.1E−11 JM-1 B-ALL 2.4E−11 KCL-22 CML 3.0E−11 Granta519 NHL1.2E−12

All publications, patents, patent applications, internet sites, andaccession numbers/database sequences (including both polynucleotide andpolypeptide sequences) cited herein are hereby incorporated by referencein their entirety for all purposes to the same extent as if eachindividual publication, patent, patent application, internet site, oraccession number/database sequence were specifically and individuallyindicated to be so incorporated by reference.

1. A cytotoxic compound represented by any one of the followingformulas:

or a pharmaceutically acceptable salt thereof, wherein: one of L′, L″,and L′″ is represented by the following formula:—Z₁—P—Z₂—R_(x)-J  (A) and the other two are the same or different, andare independently selected from —H, an optionally substituted linear,branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbonatoms, a polyethylene glycol unit —(CH₂CH₂O)_(n)—R^(c), halogen,guanidinium [—NH(C═NH)NH₂], —OR, —NR′R″, —NO₂, —NR′COR″, —SR, —SOR′,—SO₂R′, —SO₃H, —OSO₃H, —SO₂NR′R″, cyano, an azido, —COR′, —OCOR′, and—OCONR′R″; one of the Z₁ and Z₂ is —C(═O)—, and the other is —NR₅—; P isan amino acid residue or a peptide containing between 2 to 20 amino acidresidues; R_(x) is an optionally substituted linear, branched or cyclicalkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms; J is amoiety comprising a reactive group that is capable of covalently linkingthe cytotoxic compound to a cell-binding agent; the double line

between N and C represents a single bond or a double bond, provided thatwhen it is a double bond X is absent and Y is —H, or a linear orbranched alkyl having 1 to 4 carbon atoms, and when it is a single bond,X is —H or an amine protecting moiety; Y is a leaving group selectedfrom —OR, —OCOR′, —OCOOR′, —OCONR′R″, —NR′R″, —NR′COR″, —NR′NR′R″, anoptionally substituted 5- or 6-membered nitrogen-containing heterocycle(e.g., piperidine, tetrahydropyrrole, pyrazole, morpholine, etc.attached through the nitrogen atom), a guanidinum represented by—NR′(C═NH)NR′R″, an amino acid, or a peptide represented by —NRCOP′,—SR, —SOR′, halogen, cyano, azido, —OSO₃H, sulfite (—SO₃H or —SO₂H),metabisulfite (H₂S₂O₅), mono-, di-, tri-, and tetra-thiophosphate(PO₃SH₃, PO₂S2H₂, POS₃H₂, PS₄H₂), thio phosphate ester(R^(i)O)₂PS(OR^(i)), R^(i)S—, R^(i)SO, R^(i)SO₂, R^(i)SO₃, thiosulfate(HS₂O₃), dithionite (HS₂O₄), phosphorodithioate (P(═S)(OR^(k′))(S)(OH)),hydroxamic acid (R^(k′)C(═O)NOH), and formaldehyde sulfoxylate (HOCH₂SO₂⁻) or a mixture thereof, wherein R^(i) is a linear or branched alkylhaving 1 to 10 carbon atoms and is substituted with at least onesubstituent selected from —N(R^(j))₂, —CO₂H, —SO₃H, and —PO₃H; R^(i) canbe further optionally substituted with a substituent for an alkyldescribed herein; R^(j) is a linear or branched alkyl having 1 to 6carbon atoms; R^(k′) is a linear, branched or cyclic alkyl, alkenyl oralkynyl having 1 to 10 carbon atoms, aryl, heterocyclyl or heteroaryl;P′ is an amino acid residue or a polypeptide containing between 2 to 20amino acid residues, R, for each occurrence, is independently selectedfrom the group consisting of —H, an optionally substituted linear,branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbonatoms, a polyethylene glycol unit —(CH₂CH₂O)_(n)—R^(c), an optionallysubstituted aryl having 6 to 18 carbon atoms, an optionally substituted5- to 18-membered heteroaryl ring containing one or more heteroatomsindependently selected from nitrogen, oxygen, and sulfur, or anoptionally substituted 3- to 18-membered heterocyclic ring containing 1to 6 heteroatoms independently selected from O, S, N and P; R′ and R″are each independently selected from —H, —OH, —OR, —NHR, —NR₂, —COR, anoptionally substituted linear, branched or cyclic alkyl, alkenyl oralkynyl having from 1 to 10 carbon atoms, a polyethylene glycol unit—(CH₂CH₂O)_(n)—R^(c), and an optionally substituted 3- to 18-memberedheterocyclic ring having 1 to 6 heteroatoms independently selected fromO, S, N and P; R^(c) is —H or an optionally substituted linear orbranched alkyl having 1 to 4 carbon atoms; n is an integer from 1 to 24;X′ is selected from —H, an amine-protecting group, an optionallysubstituted linear, branched or cyclic alkyl, alkenyl or alkynyl havingfrom 1 to 10 carbon atoms, a polyethylene glycol unit—(CH₂CH₂O)_(n)—R^(c), an optionally substituted aryl having 6 to 18carbon atoms, an optionally substituted 5- to 18-membered heteroarylring containing one or more heteroatoms independently selected fromnitrogen, oxygen, and sulfur, and an optionally substituted 3- to18-membered heterocyclic ring containing 1 to 6 heteroatomsindependently selected from O, S, N and P; Y′ is selected from —H, anoxo group, an optionally substituted linear, branched or cyclic alkyl,alkenyl or alkynyl having from 1 to 10 carbon atoms, an optionallysubstituted 6- to 18-membered aryl, an optionally substituted 5- to18-membered heteroaryl ring containing one or more heteroatomsindependently selected from nitrogen, oxygen, and sulfur, an optionallysubstituted 3- to 18-membered heterocyclic ring having 1 to 6heteroatoms; R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ are eachindependently selected from the group consisting of —H, an optionallysubstituted linear, branched or cyclic alkyl, alkenyl or alkynyl havingfrom 1 to 10 carbon atoms, a polyethylene glycol unit—(CH₂CH₂O)_(n)—R^(c), halogen, guanidinium [—NH(C═NH)NH₂], —OR, —NR′R″,—NO₂, —NCO, —NR′COR″, —SR, —SOR′, —SO₂R′, —SO₃—H, —OSO₃H, —SO₂NR′R″,cyano, an azido, —COR′, —OCOR′, and —OCONR′R″; R₆ is —H, —R, —OR, —SR,—NR′R″, —NO₂, or halogen; G is —CH— or —N—; A and A′ are the same ordifferent, and are independently selected from —O—, oxo (—C(═O)—),—CRR′O—, —CRR′—, —S—, —CRR′S—, —NR₅ and —CRR′N(R₅)—; and R₅ for eachoccurrence is independently —H or an optionally substituted linear orbranched alkyl having 1 to 10 carbon atoms. 2-8. (canceled)
 9. Thecompound of claim 1, wherein L′ is represented by the following formula:—NR₅—P—C(═O)—(CR_(a)R_(b))_(m)-J  (B1);—NR₅—P—C(═O)—Cy-(CR_(a)R_(b))_(m′)-J  (B2);—C(═O)—P—NR₅—(CR_(a)R_(b))_(m)-J  (C1), or—C(═O)—P—NR₅-Cy-(CR_(a)R_(b))_(m′)-J  (C2) wherein: J is —COE; R_(a) andR_(b), for each occurrence, are each independently —H, (C₁-C₃)alkyl or acharged substituent or an ionizable group Q; m is an integer from 1 to6; m′ is 0 or an integer from 1 to 6; and Cy is a cyclic alkyl having 5or 6 ring carbon atoms optionally substituted with halogen, —OH,(C₁-C₃)alkyl, (C₁-C₃)alkoxy, or halo(C₁-C₃)alkyl. 10-11. (canceled) 12.The compound of claim 1, wherein L′ is represented by the followingformula:—NR₅—P—C(═O)—(CR_(a)R_(b))_(m)—S—Z^(s)  (B3); or—C(═O)—P—NR₅—(CR_(a)R_(b))_(m)—S—Z^(s)  (C3), wherein: R_(a) and R_(b),for each occurrence, are each independently —H, (C₁-C₃)alkyl or acharged substituent or an ionizable group Q; m is an integer from 1 to6; Z^(s) is —H, —SR^(d), —C(═O)R^(d1) or is selected from any one of thefollowing formulas:

wherein: q is an integer from 1 to 5; n′ is an integer from 2 to 6; U is—H or SO₃M; M is H⁺, Na⁺ or K⁺; R^(d) is a linear or branched alkylhaving 1 to 6 carbon atoms or is selected from phenyl, nitrophenyl(e.g., 2 or 4-nitrophenyl), dinitrophenyl (e.g., 2,4-dinitrophenyl),carboxynitrophenyl (e.g., 3-carboxy-4-nitrophenyl), pyridyl ornitropyridyl (e.g., 4-nitropyridyl); and R^(d1) is a linear or branchedalkyl having 1 to 6 carbon atoms. 13-17. (canceled)
 18. The compound ofclaim 9, wherein P is a peptide containing 2 to 5 amino acid residues.19. The compound of claim 18, wherein P is selected from Gly-Gly-Gly,Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit,Leu-Cit, Lle-Cit, Trp, Cit, Phe-Ala, Phe-N⁹-tosyl-Arg, Phe-N⁹-nitro-Arg,Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu,Val-Ala-Val, Ala-Leu-Ala-Leu, β-Ala-Leu-Ala-Leu and Gly-Phe-Leu-Gly,Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit,D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg,D-Arg-D-Arg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met, andMet-Ala. 20-31. (canceled)
 32. The compound of claim 19, wherein: thedouble line

between N and C represents a single bond or double bond, provided thatwhen it is a double bond X is absent and Y is —H, and when it is asingle bond, X is —H, Y is —OH or —SO₃M; R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′and R₄′ are all —H; R₆ is —OMe; X′ and Y′ are both —H; A and A′ are —O—;and M is H, Na⁺ or K⁺.
 33. The compound of claim 1, wherein the compoundis selected from any one of the following formulas:

or a pharmaceutically acceptable salt thereof, wherein: R₁₀₀ is —OH,—OMe or

Y is —H, —OH or —SO₃M; M is H⁺, Na⁺ or K⁺; Z^(s) is —H, —SR^(d),—C(═O)R^(d1) or is selected from any one of the following formulas:

wherein: q is an integer fro 1 to 5; n′ is an integer from 2 to 6; U is—H or SO₃M; and R^(d) is a linear or branched alkyl having 1 to 6 carbonatoms or is selected from phenyl, nitrophenyl (e.g., 2 or4-nitrophenyl), dinitrophenyl (e.g., 2,4-dinitrophenyl),carboxynitrophenyl (e.g., 3-carboxy-4-nitrophenyl), pyridyl andnitropyridyl (e.g., 4-nitropyridyl); and R^(d1) is a linear or branchedalkyl having 1 to 6 carbon atoms.
 34. (canceled)
 35. A conjugatecomprising a cytotoxic compound and a cell-binding agent (CBA), whereinthe cytotoxic compound is covalently linked to the CBA, and wherein saidcytotoxic compound is represented by any one of the following formulas:

or a pharmaceutically acceptable salt thereof, wherein: one of L′, L″,and L′″ is represented by the following formula:—Z₁—P—Z₂—R_(x)-J′  (A′) and the other two are the same or different, andare independently selected from —H, an optionally substituted linear,branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbonatoms, a polyethylene glycol unit —(CH₂CH₂O)_(n)—R^(c), halogen,guanidinium [—NH(C═NH)NH₂], —OR, —NR′R″, —NO₂, —NR′COR″, —SR, asulfoxide represented by —SOR′, a sulfone represented by —SO₂R′, asulfonate —SO₃M, a sulfate —OSO₃M, a sulfonamide represented by—SO₂NR′R″, cyano, an azido, —COR′, —OCOR′, and —OCONR′R″; one of the Z₁and Z₂ is —C(═O)—, and the other is —NR₅—; P is an amino acid residue ora peptide containing between 2 to 20 amino acid residues; R_(x) is anoptionally substituted linear, branched or cyclic alkyl, alkenyl oralkynyl having from 1 to 10 carbon atoms; J′ is a moiety comprising thelinking group that is covalently linked to the cell-binding agent; thedouble line

between N and C represents a single bond or a double bond, provided thatwhen it is a double bond X is absent and Y is —H, or a linear orbranched alkyl having 1 to 4 carbon atoms, and when it is a single bond,X is —H or an amine protecting moiety; Y is a leaving group selectedfrom —OR, —OCOR′, —OCOOR′, —OCONR′R″, —NR′R″, —NR′COR″, —NR′NR′R″, anoptionally substituted 5- or 6-membered nitrogen-containing heterocycle(e.g., piperidine, tetrahydropyrrole, pyrazole, morpholine, etc.), aguanidinum represented by —NR′(C═NH)NR′R″, an amino acid residue, or apeptide represented by —NRCOP′, —SR, —SOR′, halogen, cyano, azido,—OSO₃H, sulfite (—SO₃H or —SO₂H), metabisulfite (H₂S₂O₅), mono-, di-,tri-, and tetra-thiophosphate (PO₃SH₃, PO₂S₂H₂, POS₃H₂, PS₄H₂), thiophosphate ester (R^(i)O)₂PS(OR^(i)), R^(i)S—, R^(i)SO, R^(i)SO₂,R^(i)SO₃, thiosulfate (HS₂O₃), dithionite (HS₂O₄), phosphorodithioate(P(═S)(OR^(k′))(S)(OH)), hydroxamic acid (R^(k′)C(═O)NOH), andformaldehyde sulfoxylate (HOCH₂SO₂ ⁻) or a mixture thereof, whereinR^(i) is a linear or branched alkyl having 1 to 10 carbon atoms and issubstituted with at least one substituent selected from —N(R^(j))₂,—CO₂H, —SO₃H, and —PO₃H; R^(i) can be further optionally substitutedwith a substituent for an alkyl described herein; R^(j) is a linear orbranched alkyl having 1 to 6 carbon atoms; R^(k′) is a linear, branchedor cyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms, aryl,heterocyclyl or heteroaryl; P′ is an amino acid residue or a polypeptidecontaining 2 to 20 amino acid residues; R, for each occurrence, isindependently selected from the group consisting of —H, an optionallysubstituted linear, branched or cyclic alkyl, alkenyl or alkynyl havingfrom 1 to 10 carbon atoms, a polyethylene glycol unit—(CH₂CH₂O)_(n)—R^(c), an optionally substituted aryl having 6 to 18carbon atoms, an optionally substituted 5- to 18-membered heteroarylring containing one or more heteroatoms independently selected fromnitrogen, oxygen, and sulfur, or an optionally substituted 3- to18-membered heterocyclic ring containing 1 to 6 heteroatomsindependently selected from O, S, N and P; R′ and R″ are eachindependently selected from —H, —OH, —OR, —NHR, —NR₂, —COR, anoptionally substituted linear, branched or cyclic alkyl, alkenyl oralkynyl having from 1 to 10 carbon atoms, a polyethylene glycol unit—(CH₂CH₂O)_(n)—R^(c), and an optionally substituted 3- to 18-memberedheterocyclic ring having 1 to 6 heteroatoms independently selected fromO, S, N and P; R^(c) is —H or a substituted or unsubstituted linear orbranched alkyl having 1 to 4 carbon atoms; n is an integer from 1 to 24;X′ is selected from —H, an amine-protecting group, an optionallysubstituted linear, branched or cyclic alkyl, alkenyl or alkynyl havingfrom 1 to 10 carbon atoms, a polyethylene glycol unit—(CH₂CH₂O)_(n)—R^(c), an optionally substituted aryl having 6 to 18carbon atoms, an optionally substituted 5- to 18-membered heteroarylring containing one or more heteroatoms independently selected fromnitrogen, oxygen, and sulfur, and an optionally substituted 3- to18-membered heterocyclic ring containing 1 to 6 heteroatomsindependently selected from O, S, N and P; Y′ is selected from —H, anoxo group, an optionally substituted linear, branched or cyclic alkyl,alkenyl or alkynyl having from 1 to 10 carbon atoms, an optionallysubstituted 6- to 18-membered aryl, an optionally substituted 5- to18-membered heteroaryl ring containing one or more heteroatomsindependently selected from nitrogen, oxygen, and sulfur, an optionallysubstituted 3- to 18-membered heterocyclic ring having 1 to 6heteroatoms; R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′ and R₄′ are eachindependently selected from the group consisting of —H, an optionallysubstituted linear, branched or cyclic alkyl, alkenyl or alkynyl havingfrom 1 to 10 carbon atoms, a polyethylene glycol unit—(CH₂CH₂O)_(n)—R^(c), halogen, guanidinium [—NH(C═NH)NH₂], —OR, —NR′R″,—NO₂, —NCO, —NR′COR″, —SR, a sulfoxide represented by —SOR′, a sulfonerepresented by —SO₂R′, —SO₃H, —OSO₃H, —SO₂NR′R″, cyano, an azido, —COR′,—OCOR′, and —OCONR′R″; R₆ is —H, —R, —OR, —SR, —NR′R″, —NO₂, or halogen;G is —CH— or —N—; A and A′ are the same or different, and areindependently selected from —O—, oxo (—C(═O)—), —CRR′O—, —CRR′—, —S—,—CRR′S—, —NR₅ and —CRR′N(R₅)—; R₅ for each occurrence is independently—H or an optionally substituted linear or branched alkyl having 1 to 10carbon atoms. 36-41. (canceled)
 42. The conjugate of claim 35, whereinL′ is represented by the following formula:—NR₅—P—C(═O)—(CR_(a)R_(b))_(m)-J′  (B1′);—NR₅—P—C(═O)-Cy-(CR_(a)R_(b))_(m′)-J′  (B2′);—C(═O)—P—NR₅—(CR_(a)R_(b))_(m)-J′  (C1′), or—C(═O)—P—NR₅-Cy-(CR_(a)R_(b))_(m′)-J′  (C2′) wherein: J′ is —C(═O)—;R_(a) and R_(b), for each occurrence, are each independently —H,(C₁-C₃)alkyl or a charged substituent or an ionizable group Q; m is aninteger from 1 to 6; m′ is 0 or an integer from 1 to 6; and Cy is acyclic alkyl having 5 or 6 ring carbon atoms optionally substituted withhalogen, —OH, (C₁-C₃)alkyl, (C₁-C₃)alkoxy, or halo(C₁-C₃)alkyl. 43-44.(canceled)
 45. The conjugate of claim 35, wherein L′ is represented bythe following formula:—NR₅—P—C(═O)—(CR_(a)R_(b))_(m)—S—Z^(s1)  (B3′); or—C(═O)—P—NR₅—(CR_(a)R_(b))_(m)—S—Z^(s1)  (C3′), wherein: R_(a) andR_(b), for each occurrence, are each independently —H, (C₁-C₃)alkyl, ora charged substituent or an ionizable group Q; m is an integer from 1 to6; Z^(s1) is selected from any one of the following formulas:

wherein: q is an integer fro 1 to 5; n′ is an integer from 2 to 6; U is—H or SO₃M; and M is H⁺, Na⁺ or K⁺. 46-50. (canceled)
 51. The conjugateof claim 42, wherein P is a peptide containing 2 to 5 amino acidresidues.
 52. The conjugate of claim 42, wherein P is selected fromGly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys,Ala-Lys, Phe-Cit, Leu-Cit, Lle-Cit, Trp, Cit, Phe-Ala, Phe-N⁹-tosyl-Arg,Phe-N⁹-nitro-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu,Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu, β-Ala-Leu-Ala-Leu,Gly-Phe-Leu-Gly, Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys,Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys,D-Val-D-Arg, D-Arg-D-Arg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala,Ala-Met, and Met-Ala. 53-64. (canceled)
 65. The conjugate of claim 52,wherein: the double line

between N and C represents a single bond or double bond, provided thatwhen it is a double bond X is absent and Y is —H, and when it is asingle bond, X is —H, Y is —OH or —SO₃M; R₁, R₂, R₃, R₄, R₁′, R₂′, R₃′and R₄′ are all —H; R₆ is —OMe; A and A′ are —O—; and M is H, Na⁺ or K⁺.66. The conjugate of claim 35, wherein the compound is selected from anyone of the following formulas:

or a pharmaceutically acceptable salt thereof, wherein: r is an integerfrom 1 to 10; Y is —H, —OH or —SO₃M; and M is H⁺, Na⁺ or K⁺. 67.(canceled)
 68. The conjugate of claim 35, wherein the cell-binding agent(CBA) binds to target cells selected from tumor cells, virus infectedcells, microorganism infected cells, parasite infected cells, autoimmunecells, activated cells, myeloid cells, activated T-cells, B cells, ormelanocytes; cells expressing the CD4, CD6, CD19, CD20, CD22, CD30,CD33, CD37, CD38, CD40, CD44, CD56, EpCAM, CanAg, CALLA, or Her-2antigens; Her-3 antigens; or cells expressing insulin growth factorreceptor, epidermal growth factor receptor, and folate receptor.
 69. Theconjugate of claim 35, wherein the cell-binding agent is an antibody, asingle chain antibody, an antibody fragment that specifically binds tothe target cell, a monoclonal antibody, a single chain monoclonalantibody, or a monoclonal antibody fragment that specifically binds to atarget cell, a chimeric antibody, a chimeric antibody fragment thatspecifically binds to the target cell, a domain antibody, a domainantibody fragment that specifically binds to the target cell, alymphokine, a hormone, a vitamin, a growth factor, a colony stimulatingfactor, or a nutrient-transport molecule.
 70. A pharmaceuticalcomposition comprising the conjugate of claim 35 and a pharmaceuticallyacceptable carrier.
 71. A method of inhibiting abnormal cell growth ortreating a proliferative disorder, an autoimmune disorder, destructivebone disorder, infectious disease, viral disease, fibrotic disease,neurodegenerative disorder, pancreatitis or kidney disease in a mammal,comprising administering to said mammal a therapeutically effectiveamount of a conjugate of claim 35, and optionally, a chemotherapeuticagent. 72-77. (canceled)